Operation PLUTO and the HAIS Cable

 By Bill Burns & Stewart Ash 

A large part of the borough of Greenwich is currently being re-developed to provide much-needed housing and new commercial premises. This includes the regeneration of several old industrial sites along the river front. One such ‘brown field’ development is the Faraday Works, in the north-west corner of the old Siemens Brothers factory.

The factory was established in 1863 by Charles William Siemens (1823-83), on land leased from the Bowater Estate, and the site is still situated on the south bank of the River Thames, at the border of Charlton and Woolwich. It is bounded on the other three sides by Eastmoor Street, Warspite Road, and the Woolwich Road. Charles was born Carl Wilhelm Siemens on 4 April 1823 in Berlin, and came to England in March 1848 to set up a branch of Siemens & Halske. This company had been founded in Berlin by his elder brother Ernst Werner Siemens (1816-92) and Johann Georg Halske (1814-90). By 1858, Carl Wilhelm had registered the Siemens & Halske Agency in London, providing engineering consultancy to the emerging telegraph market. Its clients included the British Government, for both the terrestrial electrical telegraph and the pioneering submarine telegraph cables markets. At the same time, another brother, Karl Heinrich Von Siemens (1829-1906), set up a Siemens & Halske factory in St Petersburg to sell telegraph equipment and cables to the Russians. 

On 19 March 1859, Carl Wilhelm became a naturalized British subject under a warrant granted by Queen Victoria, changing his name to Charles William Siemens. This was in preparation for his marriage to Anne Gordon (1821-1901) on 23 July that year. She was the sister of Lewis Brodie Gordon (1815-76), Professor of Civil Engineering and Mechanics at Glasgow University. In 1865, a rift developed between William Siemens and Johann Halske over the submarine telegraph cable market, which Halske considered too risky, so they went their separate ways. Halske retained a large equity stake in the London company, but it was re-registered as Siemens Brothers. In 1869, Karl Hendrich came to join William in London, and he too would later become a naturalised British citizen. 

Artist’s Impression of the Original Siemens Brothers Site in 1863, by E Neale c 1927 

Siemens Brothers prospered and the site expanded to 35 acres (14 Hectares), employing around 10,000 people at its peak, second only to the Royal Arsenal in the size of the site and its number of employees. Despite its strong German links, which would result in confiscation of share capital and internment and/or deportation of many German national employees during both World Wars, Siemens Brothers was responsible for several major technical developments that assisted the allies in both WWI and WWII. In the First World War, these included field telephone systems and trench cable, but perhaps the most significant development was the ruggedised light bulbs for the Aldis and OL signalling lamps, used by the Royal Navy and Army respectively in both wars. In the Second World War, the demand for telecommunication cable was again high because of bomb damage caused by German air-raids, but significant military projects included the ‘Clyde Loop’, that protected and kept the mouth of the River Clyde free of mines, and the High-Speed Motor Uniselector used in the revolutionary RADAR system, then known as ‘Chain Home’. Siemens also produced the extremely robust light bulbs for the Churchill Tank, without which it would have been inoperable, due to the massive vibrations produced by its engine and drive system. However, perhaps the most audacious and ingenious of these products was the rapid development and manufacture, in complete secrecy, of the H.A.I.S. Cable for Operation PLUTO (Pipe Line Under The Ocean). 

The story of PLUTO begins in early April 1942, when Lord Louis Mountbatten (1900-79), the Queen’s second cousin, and at that time Chief of Combined Operations, put a proposition to Geoffrey Lloyd (1902-84), the Conservative MP for Birmingham Ladywood, at that time Secretary for Petroleum and head of the Petroleum Warfare Department of the Ministry of Fuel and Power. Mountbatten’s proposal was that if a military campaign into Europe against the Nazis was to be successful, then there would need to be a pipeline across the English Channel to provide petrol, oil and lubricants in bulk to support the armed forces. Lloyd put this concept to the experts in his department and their consultants who had, prior to the outbreak of war, been working on pipelines across the Bristol Channel, the River Mersey and the Thames. Their advice was that tidal and weather conditions in the English Channel, together with the risk of enemy action, would make it impossible to implement using any currently known land or sea construction method, which required pipes of 6” (inches) or more in diameter. However, the problem reached the ears of Arthur Clifford Hartley (1889-1960), Chief Engineer of the Anglo-Iranian Oil Co Ltd. A few years earlier, his company had solved the problem of transportation of oil, over a very hilly route, by the development of a 3” pipe working at 1,500 pounds per square inch (psi) [103.4 bar]. Hartley recognised that such a pipe could deliver 100,000 gallons of fuel per day, the equivalent of 25,000 ‘Jerrycans’, the method used to refuel vehicles in the field. So, on 15 April 1942, Hartley made a suggestion to his Chairman, Sir William Fraser (1888-1970), who was also Honorary Petroleum Advisor to the War Office, that such a line could make a significant contribution to this problem and that if multiple lines were built it would have the major advantage of not having all their eggs in one basket. 

One obvious problem was that the pipeline would need to be laid quickly to overcome the tides and currents, and ideally it should be laid in one operation without joints at sea. This would also have the advantage of limiting the risk of enemy action disrupting the operation. Hartley thought it might be possible to use submarine cable technology to contrive a cable without a core that could be deployed by a cableship. Fraser encouraged Hartley to develop his idea further and promised him his full support, so the next day Hartley called on the Managing Director of Siemens Brothers, Dr Henry Robert Wright (1879-1951). Wright thought that the concept was viable and immediately arranged for his Woolwich factory to design and make a 200-yard (183m) test length which could withstand an internal pressure of 500lb psi (34.47bar). It was manufactured from materials that were already available in stock and consisted of a 2” bore tube of hardened lead, reinforced with two layers of 10mm steel tapes, and over-armoured with galvanised steel wires. Production was completed within a week and a rigorous static testing regimen then commenced, which included strain and pressure tests to failure. The results were promising and demonstrated that a much higher working pressure of up to 750psi (51.7bar) could be achieved. 

The design of the cable was based on Siemens Brothers’ experience of developing gas-filled power cables, combined with their vast experience in making and laying submarine cables. The design concept was intended to deliver 30,000 gallons a day over the 20 nautical mile (nm) span from Dover to Calais. Just fifteen days after the initial contact with Dr Wright, Geoffrey Lloyd and the Services Chiefs involved in Operation PLUTO visited the factory to see the test cable coiled on board the Post Office cableship HMTS Alert (2) anchored off the Woolwich Works in the River Thames. The party included Lieutenant-General Bernard Law Montgomery (1887-1976). So pleased were they with the progress that Lloyd requested a short sample of the test cable that he could take to show the Prime Minister, Winston Churchill (1874-1965). 

Geoffrey Lloyd and the Service Chiefs. Including General Montgomery on the far left 

Shortly after this visit instructions came from 10 Downing Street to proceed with the project with all speed. 

The Post Office, the Admiralty, Combined Operations, the War Office and Anglo-Iranian were called together at the Petroleum Division HQ to arrange the manufacture of further lengths and prepare a complete test programme. Anglo-Iranian undertook, as agents of the Petroleum Division, to develop, order, progress and supervise the whole of the pipe, pipe joints, pumping installations, etc. that would be required, and Siemens Brothers, without waiting for official orders or priorities, quickly produced more cable. Secrecy from the enemy was paramount and the cable was given the codename ‘H.A.I.S.’ an acronym derived from Hartley, Anglo-Iranian & Siemens. 

One of the most important features of this project was the necessity for all discussions, development and manufacture to be carried out in absolute secrecy, as if information were to have leaked concerning the nature of what was being planned, the enemy would have taken any risk to prevent the cable being completed, or to destroy it when it was being laid in the English Channel. Elaborate precautions were put in place; one section of the Siemens Works was isolated and special passes were issued to every person, whether senior management or factory worker, who was required to enter the area. In addition, the staff engaged in the work were called into the factory library, where the Works Manager informed them not of the purpose to which the new cable was to be put, but of the fact that they were to be engaged in a job vital to the war effort. Therefore, it was of the utmost importance for them not to talk to anyone, either inside the Works or outside, concerning the work on which they were engaged. Everyone whom it became necessary to allow to enter the secure area was compelled to sign a statement signifying their complete understanding of the requirements of the Official Secrets Act. It appears that Government security officers were brought in to test the strength of the systems in place, and they made repeated but unsuccessful attempts to enter the restricted areas of the Works. After the war, Siemens was formally congratulated upon the efficiency of the precautions and safeguards that it had put in place and operated throughout the project. 

The handling trial that had taken place on 1 May 1942 showed that the test sample could be coiled into a tank, loaded onto a cableship, and discharged back into the factory without impairing its performance. The next step was to manufacture a much longer length, deploy it, and test it in situ. 

The next section of test cable to be manufactured was 1,100 yards (1,006m) in length. On 10 May 1942, it was laid by the Alert (2) in a loop off Chatham, in the Medway. The ends were brought ashore to pumps that had been borrowed from the Manchester Ship Canal Co, and pumping tests at 600psi (41.37bar) were commenced. However, after two days faults occurred in the cable structure, so the cable was recovered and the defective sections examined by the Post Office, Siemens Brothers and W T Henley & Co. Under normal circumstances, Henley’s would have been a major competitor of Siemens Brothers but it was at Siemens’ suggestion that Henley’s was invited to join the project to provide additional manufacturing capability, as its factory at Gravesend was adjacent to the River Thames, which would facilitate transfer of the cable to cableships. This collaboration between commercial competitors would continue throughout Operation PLUTO. 

The cable failure mechanism was quickly identified as the extrusion of the lead through gaps in the helical steel strengthening tapes, due to the two layers of tape being directly one above the other in certain places along the cable. To resolve the problem the combined resources of the Siemens and Henley’s Research and Design departments, together with the Post Office and the National Physical Laboratory, both of which had been brought in to assist, were mobilised. The result was that a new specification was drawn up within two days of the failure mechanism being identified. Lengths of this design were then ordered from both cable making companies. The new design comprised a central lead-tin-antimony pipe, 2” in diameter, wrapped with two layers of paper tape, one of cotton, four layers of steel tape (right hand lay), jute, helically lapped longitudinal steel wires (left hand lay) and further layers of jute covered with whitewash. The opposite lays of the tapes and the armour wires were designed to balance each other, making the cable torsionally neutral, so that it would not twist under handling or the influence of internal pressure. This design was calculated to allow for an internal pressure of 1,250 psi (86 bar). 

Telescoped Section of the Final 2” H.A.I.S. Cable 

In June 1942, test lengths of both firms' manufacture were laid by the Post Office ship HMTS Iris (2) in water of similar depth to the English Channel in the Clyde estuary. Siemens' cable was the first to be deployed; it was laid over the bow with the ship steaming ahead and with the central tube containing air at atmospheric pressure. After the cable was recovered from a depth of about 33 fathoms (61m), it was pressurised to 90psi (6.2 bar), and it appeared that the cable was leaking, as after the cable had been filled with water, the applied test pressure would not remain steady. In addition, water appeared on the outside of the cable, seeping through the outer jute serving at several places along the cable length. These locations were stripped down to the lead tube, where it was found to have been pressed in on itself into a kidney shape. The reason for this was that the tensile load applied to the cable, both on the forward drum engine and when passing over the bow sheave, had deformed the circular lead tube into an oval, and the external hydrostatic pressure of the sea had then further crushed the deformed tube Because of this, some sea water was found to have been trapped in the space formed between the lead pipe and its steel tape protection. Under application of the test pressure, the lead pipe had begun to return to its circular form, and this pushed the trapped water through the outer armouring and serving, giving the impression of leaks. 

Cross Section of Deformed Trials Cable 

Due to the increasing urgency of the project, it was decided to go ahead with the lay of the Henley’s cable in parallel with this investigation into the assumed failure of the Siemens cable. It was again laid from the bow of the Iris (2), but this time with the ship going astern to simulate the less demanding over-the-stern laying conditions. In addition, the Henley’s cable was laid while filled with water pressurised to 100 psi (6.89 bar) to balance the external hydrostatic pressure. The complete success of this test lay, combined with the confirmation that the Siemens cable had not failed, was encouraging. The Siemens cable had undergone more severe conditions during its lay than the Henley’s cable, and in so doing had proved that the design was capable of withstanding much rougher handling. This gave the PLUTO team the confidence to make the decision to manufacture six operational lengths of 26 nautical miles (48.23km), plus an additional length for a full-scale trial in the Bristol Channel, where conditions of tide and depth of water could be found that were more severe than those that would be encountered in the English Channel. 

When going into full production, it was necessary to evaluate the differences in the method of manufacture of lead tubes used by the cable making companies. Siemens believed that its technique, using a vertical press that involving a longitudinal seam, while entirely satisfactory for extruding lead sheath over ordinary cables, might need some development to make it satisfactory for making the central tube for the H.A.I.S. Cable. Rather than run the slight risk of delay, it was agreed to use lead tube made in presses, a method which avoided a longitudinal seam. Pirelli’s lead sheath, made in a continuous extrusion machine, was tested and proved satisfactory but before it could be adopted Pirelli’s works were taken out of operation by enemy action. As Henley’s lead tube, made in its ‘Judge’ straight-though presses, had been proved suitable, this type of press provided all the lead pipe used until the manufacturing capacity of further cable companies had to be brought in to produce the large quantities of cable eventually required. Lead tubes made by Pirelli’s continuous presses and by vertical presses (including those with longitudinal seams) both in the UK and the USA, were later used with complete success. 

Full scale production on this 2” cable commenced at the Woolwich Works on 14 August 1942, and the first completed 26nm (48.25km) length for the Bristol Channel trial, which had an overall diameter of 3” and weighed approximately 1,050 tons (1,067 tonnes), was ready for loading by 30 October. It had been quickly identified that no existing cableship could handle and deploy this extremely heavy cable, and that a vessel large enough to carry it would have too great a draft to get close enough inshore to land the cable ends. Therefore, the Admiralty and the Ministry of War Transport made available the S.S. London, a coaster of 1,500 tons. She was fitted out to lay the H.A.I.S. Cable under the direction of the Director of Naval Construction, and renamed H.M.S. Holdfast. She was equipped with Johnson & Phillips cable gear, lent by the Post Office, and fitted with large cable tanks and specialist bow and stern sheaves. Siemens suggested to the authorities that Commander Henry Treby-Heale (1879-1966) should be made available for the laying operations and perhaps given command. He had, until recently, been in command of the company’s cableship Faraday (2), but she had been destroyed by enemy action off Milford Haven on 26 March 1941. Treby-Heale survived the attack and had then been seconded to the Royal Naval Reserve (RNR). He was an ideal choice, as he had great experience in the laying of heavy submarine cables, and so Siemens’ suggestion was readily accepted. 

HMS Holdfast 

This just left the problem of landing the shore ends. It was concluded that these needed to be landed by smaller vessels and a quick coupling or joint was required to join the main cable to the shore end cable. 

Shore Ends & Cable Couplings 

Two satisfactory types of armoured joint were developed. The first consisted of a conventional submarine cable laid-in ‘splice’, and the second comprised a mechanical coupling assembly. The splicing method was used for making up shore-end lengths and for repair work on long sections in storage tanks or on cableships, when in dock. Altogether, some forty splices were made by Siemens' jointers, but the job proved to be too time consuming and demanded too great a skill-set to be practicable when laying under fire, or for emergency repair operations; therefore, a mechanical coupling was essential. 

The design of such a coupling was a complex issue, and initial designs were prepared by the National Physical Laboratory, the Admiralty, the Petroleum Warfare Department and Siemens. After due consideration the Siemens design was adopted, and the company became the sole supplier of all couplings used in connection with Operation PLUTO. 

The H.A.I.S. Cable Coupling 

Each coupling was a complete pressure termination for a single cable end and could be fitted in about two hours by a skilled technician. Two couplings could then be brought together for a straight-through connection and assembly could be completed in about 30 minutes. Couplings were fitted to each cable end on the ship, on shore ends, and on spare sections for replacement or repairs. Meeting the requirement to quickly connect the H.A.I.S. Cable was greatly improved by using the couplings instead of the conventional in-line splice. The coupling design included bursting discs of thin copper, which were incorporated in the joint to hold the water pressure of up to 200psi (13.8 bar) that was used when laying the cable. Once the full length was assembled these discs could then be burst by increasing the internal water pressure, allowing flow through the completed pipeline. 

Static tests were continued on the 2” cables at the makers’ factories, and pressures in excess of 3,000psi (207 bar) were maintained for several months. Throughout the autumn of 1942, the Chiefs of Combined Operations conducted tests with cable on drums at the experimental establishment at Westward Ho! in an endeavour to find ways of handling the shore ends with craft which could be operated at the beaches. The most promising method devised was to mount two cable drums with 1,000 yds. (915m) of cable on horizontal axles in a landing craft (type LCT 326) designed for landing armoured vehicles, with a view to paying the cable out over the bow ramp, which was lowered with the craft going astern. This method was used as part of the full-scale trial in December 1942. 

The Bristol Channel Trial 

With all the necessary building blocks in place, a full-scale rehearsal of Operation PLUTO took place on 29 December 1942, when a 30nm length of the H.A.I.S. Cable was laid across the Bristol Channel, and the shore-end cables were to landed from LCTs at Ilfracombe and Swansea. Although the main cable was laid successfully at 5 knots by HMS Holdfast, under the command of Henry Treby-Heale RNR, great difficulty was experienced in laying the shore ends, owing to the lack of manoeuvrability of the LCTs when going astern with heavy cable over the bow. Further development work would be required before the trail cable could be completed. 

As a result of a conference convened in January 1943 at Combined Operations Headquarters to evaluate the rehearsal, it was agreed to adopt an alternative method of landing the shore ends. This would employ the technique used by submarine cable suppliers of coiling sufficient cable horizontally in the hold of a self-propelled barge, specially fitted for paying out cable over the stern through hand-controlled compressor gear. Although this involved allotting precious Thames barges and their crews solely to this task, they were made available, and the shore ends for the trial system were completed by the end of March 1943. 

The National Oil Refineries at Swansea, the Royal Engineers (RE), and the Royal Army Service Corps (RASC) specially trained Bulk Petroleum Companies had meanwhile erected a pumping station on the sea wall at Queens Dock and connected it to their petrol tanks. The Royal Engineers, working with Combined Operations and the RASC, had, with the help of the Petroleum Board, erected a receiving terminal with tanks, pumps and loading racks in Watermouth Bay near Ilfracombe. After satisfactorily testing with water, the first petrol ever to be pumped through such a long sea line reached Watermouth on 4 April 1943. Geoffrey Lloyd was there to witness the first petrol arrive and a few days later he took a sample to the Prime Minister. 

It had always been the intention that the vulnerability of the cable to bombing or depth charges, and the possibilities of needing repairs should it be dragged by a ship's anchor, would be evaluated. However, a German air raid on Swansea proved that the cable was not damaged by a bomb that exploded within 100 ft (30.5m) of it. Also, during a gale, a ship at the Mumbles anchorage dragged the cable with her anchor. H.M.S. Holdfast was deployed and had no difficulty in locating the cable, cutting out the damaged portion and completing the repair with a new length of H.A.I.S. Cable. 

In order to prove the reliability of the cable and pumps, and to train the RE and RASC personnel who would be responsible for the operation, pumping continued day and night. Initially the system was operated at the design pressure of 750psi (51.7 bar) but later this was increased to 1,500 psi (103.5 bar). At this pressure, 56,000 gallons were pumped from Swansea to Watermouth each day and distributed by the Petroleum Board around Devon and Cornwall. The Hamel Pipe Before continuing the story of the H.A.I.S. Cable, it should be noted that, early in its development, an alternative approach was introduced and worked on in parallel. On behalf of the Petroleum Division, a Mr. Ellis and Mr. Hammick were dealing with the H.A.I.S. Cable programme, and when they saw that the cable was extremely stiff in short lengths but flexible and easily manageable in long lengths, they suggested that a steel pipe could also be used for PLUTO, as they had seen samples of small diameter pipes that were also flexible when handled in long lengths in the oilfields. 

With the assistance of Stewart & Lloyd, J. & E. Hall of Dartford, and A. I. Welding, they quickly proved that a 3” steel pipe with sufficient wall thickness to handle the necessary pump pressure could be bent round a wheel of 30ft (9.1m). diameter and pulled off again, remaining relatively straight without kinking, and sections could be flash welded together to provide any required length. However, with this bending diameter, it could not be handled like cable and stored in a cableship’s tanks. One reason for this was that the coiling process results in a complete twist being induced into each turn. Although this twist is removed while uncoiling during laying, the steel pipe would not tolerate this treatment. Mr. Ellis, therefore, suggested the use of a large wheel mounted on trunnions on the deck of a Hopper Barge, with its lower portion protruding into the sea through the hopper doors. An alternative approach, also adopted, was a huge floating drum like a gigantic cotton reel, capable of carrying any quantity of pipe likely to be required. 

Model tests of the floating drum concept were carried out at the National Physical Laboratory’s tank at Froude in Worcester. These tests confirmed that such a vessel could be towed at sufficient speed without yawing. This floating drum (vessel) was named HMS Conundrum, or ‘Conun’ as it became known. Preliminary work proved that the pipe could be laid up on the drum and pulled off without kinking. The sections could be welded together with absolute reliability; so long lengths could be carried and laid by either the wheel and barge or the Conun system. Although there was no previous experience as to how a bare steel pipe would lie and behave on the seabed, it was calculated that it would have at least a six-week operational life. As the H.A.I.S. Cable was as yet unproven, and there was significant concern as to whether there would be sufficient supplies of lead available to complete the H.A.I.S. programme and meet the operational targets, having a complementary method, even if it was short lived, was considered desirable, and so it was decided to proceed with this approach. This pipe was given the codename ‘Hamel’ after its inventors, Hammick and Ellis. A factory at Tilbury was set up to weld, store and wind Hamel Pipe. A Hopper Barge was converted to carry the drum and was later called HMS Persephone, and a Conun was also constructed. 

HMS Persephone 

The contract for pipe manufacture was awarded to Stewart & Lloyd, and this company also undertook to act as agents of the Petroleum Division for the design and construction of the pipe. Subsequently the company took on the management of the Tilbury factories. At the same time, the Director of Naval Construction took responsibility for fitting out HMS Persephone, the design of the Conun, and the supervision of its construction by Messrs Orthostyle. 

A Conun Loaded with Hamel Pipe 

Two adjacent factories were constructed at Tilbury to weld 40ft (12.2m) lengths of 3” diameter steel pipe into 4,000ft (1,219m) lengths. While being welded, the pipe was pushed down 4,000ft. conveyor channels and, on completion, thrown off on to a storage rack. Pending completion of the Tilbury factories, a few miles of 3” steel pipe were hand-welded in Portsmouth Dockyard and wound on to Persephone's drum for preliminary trials. These were entirely successful, and the work was completed by April, so that both the H.A.I.S. Cable and Hamel Pipe had successfully completed their main trials programmes by the Spring of 1943. 

It was realised very early in the Hamel Pipe trials that it was not flexible enough be used at the shore ends. It could not be deployed quickly enough, especially at the French end, where the operation would be under heavy enemy fire. For the Hamel Pipe to be used, the shore ends would have to be H.A.I.S. Cable. However, this would reduce the diameter of the pipe at both ends from 3” to 2”, causing a significant reduction in throughput. A 3” diameter H.A.I.S. Cable was needed, at least in short lengths, if the Hamel Pipe was to deliver its maximum potential. 

The 3” H.A.I.S. Cable 

The success achieved by the Bristol Channel dress rehearsal had already led to the consideration of increasing the diameter of the core of the H.A.I.S. Cable to 3”. This dimensional change had been suggested as it would offer a significant increase in capacity that would reduce the number of cables needed to reach the required supply target. The requirement for a 3” cable to provide the shore ends for Hamel Pipe added to reasons for progressing this design modification. 

The design of the new cable was similar in most respects to the 2” cable, with the exception of the increased tube diameter, and the steel tapes were increased to 22mm in thickness to deal with the greater hoop stress that the cable would have to withstand. The final overall diameter of this cable, after armouring, was about 4.5”. Work on the 3” tube design commenced at the Woolwich Works in September 1943 and in parallel, the coupling design was adapted. New designs were developed for the 3” cable, with a modified version to fit the ends of the Hamel Pipe. 

A Change of Course 

On 23 April 1943, full scale production of both solutions had been authorised by the Petroleum Division and the Chief of Combined Operations. They then handed on responsibility of the Operational Stage to the Petroleum Warfare Department under its Director General, Major-General Sir Donald Banks (1881-1975), K.C.B., D.S.O., M.C., and Force PLUTO, specially organised by the Admiralty under the command of Captain John Fenwick Hutchings (1885-1968), C.B.E., D.S.O., Royal Navy. The Quartermaster General visited the Watermouth Bay station on 24 April to see the H.A.I.S. Cable system in operation, and on 29 April he visited the Hamel factories in Tilbury, then proceeded to Henley’s factory in Gravesend and the Siemens works at Woolwich to see production of the 2” H.A.I.S. Cable. At Woolwich, he also saw HMS Holdfast loading a length of 2” H.A.I.S Cable. From his observations he decided that no further lengths of 2” cable should be made, and that 3” cable, then undergoing Works tests, should be thoroughly trialled in order to maximise the opportunity of obtaining the advantage that the 3” cable would provide almost treble the output of the 2” cable. 

During June and July 1943, recommendations were made by the Quartermaster General's Petroleum Committee, and these were confirmed by the Chiefs of Staff Committee, that Operation PLUTO should be made a high priority. Up to this point the plan had only conceived a pipeline from Dungeness to Boulogne, but for the first time, a second line from the Isle of Wight to Cherbourg was introduced into the plan. Plans were put in place for pumping stations of 3,500 and 3,000 tons per day to be built at Dungeness and the Isle of Wight respectively. Unknown to the members of the Operation PLUTO teams, this was an indication that the D-Day landings were being planned for Normandy. 

Isle of Wight to Cherbourg Crossing 

The decision to lay a pipeline from the Isle of Wight to Cherbourg would require much larger quantities of cable and pipe, and so arrangements were made to increase British manufacture as much as possible, but also to obtain 140nm (260km) of cable from the USA. In addition, it was planned to duplicate the Tilbury factory for welding, storage and winding Hamel Pipe in the USA. An American Army proposal had also been developed for laying cross-Channel lines, but when the progress made in UK with the H.A.I.S. Cable and the Hamel Pipe was seen by ‘Ike’, General Dwight David Eisenhower (1890-1969), Supreme Commander of the Allied Expeditionary Force in Europe, he decided to abandon the American scheme and concentrate on helping the British programme by supplying cable to the UK design and providing additional pumping and auxiliary plant from the USA. 

The Isle of Wight to Cherbourg route involved a sea-crossing of about 70nm (130km), instead of the 26nm (48.4km) originally visualised. This made necessary the provision of larger cableships and the use of the Conun, which would be loaded till the axles were awash. Following a successful trial lay of the 3” H.A.I.S. Cable, Operation PLUTO obtained three more ships to be converted and fitted with cable gear by the Director of Naval Construction. HMS Algerian was to carry 30nm (56.7km) of 3” cable, and the other two, HMS Latimer and HMS Sancroft, were to carry 100nm (185km) of 3” cable, weighing about 6,400 tons. Six Thames barges were also converted and equipped to handle the shore ends. In addition, a large number of auxiliary vessels were added to the Operation PLUTO fleet. 

Tests using a model Conun at the National Physical Laboratory showed that it could be handled when loaded with 70nm of Hamel Pipe, provided that two of the largest class of Ocean Rescue Tugs (the Bustler) were used ahead, and a smaller tug astern for steering. The production of five more Conuns was then put in hand. When fully loaded with 70nm of Hamel Pipe, each Conun weighed 1,600 tons, or the equivalent of a Royal Navy Destroyer. 

Pumping Stations, Storage Tanks & Camouflage 

Diesel-driven reciprocating pumps, each capable of handling about 180 tons per day, had been ordered in large numbers for the pumping stations. However, with the increase in capacity required by the longer crossing, it was decided that centrifugal pumps with a capacity of 1,100 tons per day, powered from the electrical grid, should also be installed, in order to reduce the number of operating and maintenance staff required. 

Anglo-Iranian undertook the supervision of the construction of the pumping stations and storage tanks. This involved civilian contractors, the RE, RASC, and the Pioneers Corp. The RASC were effectively a Bulk Petroleum Company specially trained for the operation. The Petroleum Board constructed the land lines and Force PLUTO laid a large number of H.A.I.S Cables and Hamel Pipes across the Solent to provide redundant lines to the Isle of Wight. These installations were an ideal opportunity to train the personnel of the large force that was being assembled and to develop and trial the ships and their equipment. During these operations, it was established that the cable and pipe could withstand all reasonable end tensile pulls, but that both would be severely kinked and damaged if allowed to hang vertically from the laying vessel, or if they were run back upon. 

Unlike many war secrets, Operation PLUTO could have been given away very easily. If the Germans had got hold of such information as ‘A petrol pipe like a hollow submarine cable across the Channel’, the project might well have foundered. Clearly, the pumping stations and storage tanks might easily be identified by air reconnaissance, so much effort was put into camouflage techniques to reduce the risk of discovery and attack, and the pumping station construction was put under the supervision of a Camouflage Officer. Any plant which might be seen from the air was moved into position under the cover of darkness, and existing buildings such as bungalows, garages and ice cream factories were all used as pump houses. Control photographs were taken at regular intervals by the RAF to reduce the risk of discovery. These precautions were often expensive and time-consuming but were successful, which was proven by the absence of any known attempts by the enemy to interfere with the pumping process during the period that PLUTO was operational. 

Enemy Action 

The development and manufacture of the H.A.I.S. Cable and the Hamel Pipe, together with the conversion of vessels and the construction of Conuns, was completed in just over two years. This would have been an exceptional achievement in peace time, but it was carried out in what appears to have been complete secrecy. Given the number of organisations that had to collaborate, it is impressive that the Germans did not get wind of Operation PLUTO or its objectives. However, there was a war going on, and throughout the development programme London was the target of continuous bombing raids. All the major Operation PLUTO manufacturing sites were on the River Thames at Gravesend, Tilbury and Woolwich, close to major docks, and thus obvious targets. The Luftwaffe’s general approach to bombing raids on London was to gather their planes in the North Sea off the Thames Estuary or in the Channel off Folkestone, then follow the river or the A20 respectively into London. In both cases the Siemens Brothers Works at Woolwich was directly in the firing line. 

Although Siemens Brothers was predominantly a British company, at the start of the war its German counterpart still held a large equity stake, and there were still a few German-born employees. The two companies had continued to collaborate on development programmes right up to the outbreak of war, and the Nazis thus knew all about Siemens Brother and its products, so the Woolwich Works became a specific target. This can be confirmed because of a unique photograph discovered by Allied troops when they liberated the Luftwaffe Headquarters in Belgium. 

Luftwaffe Aerial Photograph of the Siemens Woolwich Works 

The thick black line in the image above is shown as a thick red line on the original and outlines the Works at Woolwich with great accuracy. The index at the bottom of the photograph gives descriptions of the various types of buildings and in some cases information of what they were used for. None of these footnotes refer to Operation PLUTO or the H.A.I.S. Cable. There is no doubt that the Nazis considered the Siemens Brothers Works an important target, and while all three sites had to deal with German air raids, the Siemens Works probably suffered more than the other two. 

When war was declared on 3 September 1939, the Siemens Brothers factory site covered some 35 acres (14 Hectares) and employed over 10,000 people. The first air raid on London took place on Saturday 7 September 1940 and commenced at 17:00 that evening. The following account is taken from Siemens Brothers official reports: 

Around 5,000 employees were working that Saturday afternoon. There was no indication of anything abnormal, and when the sirens sounded, an established routine was quietly followed. Air Raid Precautions (ARP) personnel reported to their stations, and all other employees evacuated to the shelters, as they had done on many previous occasions without any incidents. However, on this occasion the sirens were followed quickly by the roar of enemy bombers, and out of the blue evening sky flecked with fleecy white clouds, hundreds of enemy bombers supported by hundreds of fighters weaving around them came in a steady stream from the south-east, and almost immediately a rain of bombs commenced to fall on the Surrey Docks and Woolwich Arsenal. The crash of falling bombs was continuous, and within five minutes high columns of black smoke began to rise from the district, which appeared to be blazing over its whole area. No fewer than sixteen high-explosive bombs fell inside the boundaries of the Siemens Works and caused very great damage. 

High Explosive Bomb Damage 

This was the start of what was known as the ‘Blitz’, and this bombing campaign continued with decreasing intensity until the end of the war. In October 1945, a plan of the Works was marked up with the number of High Explosive (HE) missiles of various types that landed on the site, and their locations. In addition, the incendiary bombs that were dropped on the premises were scattered in such large numbers that it was impossible, after the first thousand, to keep accurate records of their location, but their general distribution was indicated on the plan. Although a great number of land mines were dropped in the Woolwich area, only one landed on houses, in Hardens Manorway, 50 yds (45m) to the west of the Works, shown in the plan with a parachute attached. 

1945 Site Plan showing the Location of Dropped Bombs 

In addition to the bombs recorded within the Works, in the later stages of the war three V1 rockets, known as ‘Doodlebugs’, exploded in the River Thames north of the Works, and two V2 rockets later exploded in mid-air above the Works. 

During the war, the Woolwich site was hit on no less than twenty-two occasions, and the research department in Blackheath was also damaged by HE and incendiary bombs. After 7 September 1940, the bombing of London continued with great intensity for a continuous period of 90 nights. Records show that the intense air raids by bombers only lasted for a period of six months, but occasional heavy raids persisted throughout 1941. Once the Battle of Britain was won, the daylight raids ended, and although night raids followed into 1942, they grew gradually weaker and proved far less accurate, so very few HE bombs were dropped within the Works. These night raids did continue spasmodically until the start of the V1 flying bomb attacks, which commenced on 13 June 1944. These continued day and night until they were replaced by V2 rockets, the first of which hit London on Friday 8 September 1944, and the V2 attacks continued until the launch sites in mainland Europe were final overrun by Allied troops at the end of March 1945. 

There were, of course, many bombs, flying bombs and rockets that landed in close proximity to the boundaries of the Siemens Works, and although these caused only limited blast damage to the Works, they did cause serious stoppages in production by interfering with utility services such as gas, water, electricity and telephone. Apart from the incidents that occurred in and around the factory, production was also adversely affected when there were attacks on the district as a whole, or when enemy planes were over the Works, as many thousands of man-hours were lost through the employees having to take cover in the Works air raid shelters. A further disruptor was injuries to employees and damage to their houses in the local area. Remarkably, the Siemens Works got though the war with only three fatalities and one serious injury, which required the amputation of a leg. 

Despite all this enemy action, the H.A.I.S Cable development and manufacture was successfully completed in time to meet the finally required milestone of Operation PLUTO. 

The Installation of the PLUTO system 

Full-scale trials were made with the Conun in the River Thames in February 1944, and in Bournemouth Bay in April 1944, during which the technique for towing the Conun at up to 7 knots was perfected, and the decision was taken to moor the drum at the beginning of her run and haul in the H.A.I.S. Cable shore length by means of a warp pulled in by a plough traction engine. The far-end H.A.I.S. Cable would then be laid out parallel to the shoreline and subsequently pulled in from the beach. However, both these methods proved difficult to accomplish and an alternative approach would later be adopted. 

As is well known, the D-Day landings, codenamed ‘Operation Neptune’, took place on three beaches (Gold, Juno & Sword) in Normandy on 6 June 1944. However, Operation PLUTO did not commence until 12 August, due to the delay in capturing Cherbourg and clearing the harbour of mines. The first line was laid across the English Channel from the Isle of Wight to the tip of the Cherbourg Peninsula. Two 3” H.A.I.S. Cables and two Hamel Pipelines with H.A.I.S Cable shore ends were laid on this route. Each of them was 70nm in length and the average time taken to lay the H.A.I.S Cables was about 10 hours. These were followed in the next few weeks by two Hamel Pipes. Petrol was pumped through these pipelines to support the Allied advance along the Channel Coast to Boulogne and Calais 

The advance of the Allied Armies into Belgium and Holland was so fast that it became essential to shorten the lines of supply, and so further pipelines were run across the Channel on the original planned route from Dungeness to Boulogne. The lines from Dungeness were run to a beach inside the outer harbour at Boulogne. This saved vital time by obviating the need to clear the heavily mined beach at Ambleteuse that had previously been chosen as the landing point. This change to the route involved a longer run and a more difficult approach, but a technique of laying the main lengths of H.A.I.S. Cable over the stern and dropping the ends onto the seabed was devised. These ends were to be picked up later by the shore-end barges and coupled to the shore end cables at a suitable state of a later tide, and then the shore ends were landed. Once this had been perfected, lines were laid and commissioned without incident. The average time of laying the H.A.I.S Cables on this route was only five hours and eleven H.A.I.S. Cables were finally installed. 

Six Hamel Pipes were also laid on this route. As described earlier, the method of pulling in the Hamel Pipe shore ends from the Conun had proved difficult, if not impossible, both in trials and on the Isle of Wight to Cherbourg lines. This issue was resolved by winding onto the Conun short lengths of H.A.I.S. Cable coupled to the beginning and end of each length of Hamel Pipe. These tails were led and followed respectively by a special floating wire. The Conun could then be handled like the cableship laying each tail on the seabed for the barges to recover the floating wires. They could then couple the pipes’ cable tails to the shore-end cables and deploy them with the same method that was used to complete the H.A.I.S. Cable lines. 

Force PLUTO was responsible for the installation of the line to above the low-water mark on each shore, and the RE and RASC then connected the ends with steel pipe to the valves and filters provided on the pump delivery lines in the UK and, at the far end, to valve manifolds. Main and group control rooms were set up, with telephone communication between themselves and the pump houses, and to the opposite receiving terminals. These locations were provided with diagrams on their walls on which the control officers could use coloured discs on hooks to indicate the direction of flow of oil, the pumps and lines in use, etc., at any time. 

As described earlier, the couplers contained bursting discs to contain water under pressure in the H.A.I.S. Cables during the laying operation and until the sections were connected together. When a H.A.I.S. Cable line was ready for commissioning, a pump was started at the UK end and the rate of rise of pressure was monitored and recorded. The rate of rise was slow at first, but when it reached 400psi (27.6 bar) the first disc was broken, and the pressure was seen to fall. It then began to slowly rise again until the next disc burst. This process was repeated at each disc until the liquid began to flow at the far end and this was then confirmed to the pump house, via a direct telephone line from the receiving terminal. 

Each of the 3” lines run from Dungeness were capable of delivering about 400 tons a day, or 120,000 gallons. These lines were supplied and installed sufficiently quickly to keep ahead of the capacity required to be pumped from Boulogne into the French interior. The total length of the pipelines laid on the Boulogne route was 500nm (928km), which provided a total capacity of more than 4,500 tons, or 1,350,000 gallons, per day, and 1,000,000 gallons a day were pumped across the Channel for some weeks. 

There was a valve manifold system on the beach at Boulogne, with a tank at beach level, that provided facilities for test purposes, but the flow was usually taken direct through three lines of 6” Victaulic jointed pipe up to tanks of 1,200 tons capacity on the cliffs north of Boulogne. 

As the Allied Armies advanced, the lines were extended inland through 6” Victaulic pipelines. Eventually, petrol could be pumped from Boulogne to Calais, Ghent, Antwerp, and Eindhoven, then across the Rhine at Emmerich. From Cherbourg the route was extended to Alençon and Chartres, then south of Paris to Chalons-Sur-Marne, into Luxembourg, crossing the Rhine at Mainz, and part way to Frankfurt. The pipeline’s terrestrial extensions were constructed under the control of the Quartermaster General to the Allied Forces, General Sir Thomas Sheridan Riddle-Webster (1886-1974). The final joint was completed on 10 April 1945. 

The Complete PLUTO Pipeline 

In total, over 172 million gallons were delivered over PLUTO and its extensions by the end of the Second World War! 

Siemens’ Final Contribution 

Production of the 3” H.A.I.S. Cable continued at the Woolwich Works until September 1944. By then, Siemens had completed the manufacture of a number of operational lengths of the 3” H.A.I.S Cable. One of the longest sections was 35nm (85km) and weighed over 2.200 tons when the core was filled with water. The factory coil for this was 10ft (3m) high and 65ft (19.8m) in diameter. The space required for coiling such long lengths necessitated the erection of a special building, with extra-strong cable sheaves and hauling equipment located in the roof. A long, counterpoised steel arm was designed and fitted to facilitate the handling of this extremely heavy cable. 

35nm Section of 3” H.A.I.S. Cable Being Coiled in the Tank House 

Altogether, Siemens manufactured and delivered over 200nm of 3” H A I S. Cable to the Petroleum Warfare Department. Some 280 couplings were supplied, and with each set of two couplings a complete equipment set of special tools was provided, together with numbered spare parts, to facilitate the rapid trimming of the cable ends and fitting of the couplings. 

Conclusion 

There is no doubt that Operation PLUTO was pivotal to the liberation of Northern Europe by the Allied Armies in 1944-45. Together with superior manpower and the hard-won control of the skies, PLUTO was the third key pillar in the Allied victory. Without adequate fuel supplies, no matter how successful the military campaign, the Allied forces would have quickly reached the limits of their logistical supply chain, and would have been forced to dig in. Had Operation PLUTO not happened, the advances inland after D-Day would have bogged down in a new ‘Western Front’ much closer to the beachheads, and this would have bought the Germans vital time to prolong the war. 

German military strategists understood that the enormous, highly mechanised Allied armies would have a voracious appetite for fuel. They assumed that this demand could not be met, unless major Channel ports were captured in which bulk tankers could be docked to supply the forces. This is why the German garrisons at Channel ports such as Cherbourg were instructed to hold out until the bitter end, and why, towards the end of the war, Antwerp became the focus of V1 and V2 rocket attacks. Without timely intelligence of the project, which was never forthcoming, the German High Command could not have anticipated the massive quantities of piped fuel that PLUTO delivered. Therefore, alongside its incredible engineering achievements, the measures taken to keep Operation PLUTO secret were vital to its success. 

The contribution made by the employees of Siemens Brothers to Operation PLUTO, in such difficult circumstances, was a major contributory factor to its success, and should not be forgotten. 

The authors have established that Royal London, the current owners of the Faraday Works, are working with developers U+I on revised proposals for the site, which will shortly be the subject of public consultation. The new heritage-led scheme will retain and restore four of the remaining buildings on site which formed part of the Siemens Brothers Works, including 37 Bowater Road, which has recently been designated as a Grade II listed building by Historic England, in part because of its contribution to industrial history and innovation. The developers have committed to telling the rich history of the site and recognising the vital role the site played in both World Wars, including its contribution to Operation PLUTO and the HAIS Cable. They are currently exploring initiatives such as the Red Wheel Scheme run by the National Transport Trust, as well as the use of QR tags that are being promoted for use at key historically significant stop points along the Thames River path between the Old Royal Naval College and the O2 Arena. The QR tags are intended to link to contextual history resources online, and a number could be deployed on the path through the Faraday Works. In addition, public art installations are being considered to commemorate key innovations by Siemens Brothers such as the iconic Neophone. Finally, we are pleased to report that Local historians are in close contact with the developers, U + I, to ensure that these important contributions by Siemens to the war effort, and to the development of telecommunications in general, will be commemorated in an accurate and appropriate manner. 

References 

Siemens’ Part in the Design of the HAIS Cable and Coupling, Siemens Brothers, 26 June 1945 Official Record of Damage By Enemy Action to Woolwich Works, Siemens Brothers, October 1945 Operation Pluto: A paper read to the Royal Society of Arts, A C Harley, 14 November 1945 Development of the HAIS Cable, Siemens Brothers Engineering Bulletin No.224, January 1946 Siemens Brother 1858 – 1958, J. D, Scott, published by Weidenfeld and Nicolson, 7 Cork St. London W1, 1958 

Acknowledgments 

The authors would like to thank Anthony Chapman and Linda Richardson for giving them access to the documents listed in ‘References’, and for permission to reproduce the images used in this article. We would also like to thank Clive Jefferys for his advice on the strategic benefits of Operation PLUTO and the German bombing campaigns during the Second World War.