Securing a beachhead in Europe was just the critical first step in the liberation of Western Europe during World War II. On June 6, 1944 Allied forces mounted the largest amphibious landing to date – D-Day. There will likely never be another.

It isn't that such landings are hard to pull off, but without adequate supplies a breakout from the beachhead simply isn't possible. While the Allies were able to successfully move inland, the battle could have gone another way. A generation earlier British and ANZAC (Australian and New Zealand) forces were unable to advance from the Gallipoli peninsula in Turkey during the First World War and eventually retreated.

The Allies had also learned valuable lessons in the months leading up to D-Day during the landings at Anzio in Italy. For months the American, British and Canadian forces made little progress – only scoring a major victory on June 5, 1944. The next day the Allies took part in the even larger Normandy landings. 

One concern had been how to provide the necessary fuel that the tanks, trucks and other vehicles would require. Thus was born Operation PLUTO – Pipe-Lines Underwater Transportation of Oil, later Pipe-Lines Under The Ocean. 

Developed by Arthur Hartley, chief engineer of the Anglo-Iranian Oil Company, the goal was to lay a pipeline and pump the necessary fuel to keep the tanks and trucks moving. This was considered necessary to relieve the dependence on oil tankers, which could be delayed due to bad weather but were also vulnerable to German submarines. As the tankers were also required for the war in the Pacific, the idea was that a pipeline could provide the necessary fuel to keep the Allied forces advancing.

The plan was to pipe fuel some 130 kilometers from the Isle of Wight to Port-en-Bessin Cherbourg, which was the linkup point between Omaha and Gold Beaches.

Welders had to assemble 20-foot sections of pipe into a 4,000-foot long pipeline, which was wound onto enormous floating "conundrums," which were designed to spool off the pipe when towed. The deployment system weight 1,600 tons each and resembled giant floating spools. Each was pulled by three tugboats and as the spools unwound as the pipe settled on the bottom of the English Channel.

Each mile of pipe used more than 46 tons of lead, steel tape, and armored wire, and it resembled an undersea communication cable rather than an oil pipeline. However, because of its size, no existing communications cable-laying ship could handle the task of laying the cable, and instead, a civilian passenger ship named London was specially converted to accommodate the task.

By some accounts, it was one of the greatest feats of military engineering in the history of World War II, but it was some three months late. By the time the pipeline was successfully completed – after numerous delays including when an escorting destroyer caught the line with its anchor – the Allies had successfully advanced and even Paris had been liberated.

Additional lines were laid, including one to Pas-de-Calais, but it only carried about 150 imperial barrels of gasoline per day – a fraction of what the Allied war effort required. From D-Day to V-E Day PLUTO only delivered about 8 percent of the fuel delivered to Allied forces in North-West Europe. The rest was still carried by tanker, either in bulk or in cans, while the rest was airlifted.

After the war, about 90 percent of the pipelines were recovered as salvage. However, while it failed to deliver the necessary fuel for the war effort, PLUTO was the forerunner of all flexible pipes used it the development of offshore oil fields in the post-war world.

Peter Suciu is a Michigan-based writer who has contributed to more than four dozen magazines, newspapers and websites. He is the author of several books on military headgear including A Gallery of Military Headdress, which is available on Amazon.com.