Operation Pluto

Operation Pluto (Pipe-Lines Under The Ocean) was a Second World War operation by British engineers, oil companies and armed forces to construct undersea oil pipelines under the English Channel between England and France in support of Operation Overlord, the Allied invasion of Normandy in June 1944.

The scheme was developed by Arthur Hartley, chief engineer with the Anglo-Iranian Oil Company. Allied forces on the European continent required a tremendous amount of fuel. Pipelines were considered necessary to relieve dependence on oil tankers, which could be slowed by bad weather, were susceptible to German submarines, and were also needed in the Pacific War. Geoffrey William Lloyd, the Minister for Petroleum, met Admiral Mountbatten, Chief of Combined Operations, whose area this was, in 1942 and then the Chairman of Anglo-Iranian. Hartley's idea of using adapted submarine telephone cable was adopted.

Two types of pipeline were developed. The first type was the flexible HAIS pipe with a 3 inch (75 mm) diameter lead core, weighing around 55 long tons per nautical mile (30 t/km), was essentially a development by Siemens Brothers (in conjunction with the National Physical Laboratory) of their existing undersea telegraph cables, and known as HAIS (from Hartley-Anglo-Iranian-Siemens).

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