Operation PLUTO - An Ingenious Fuel Pipeline Across the English Channel

When invading Europe, the life blood of the invading Allied forces was fuel. Engineers set to work on ensuring there'd be enough fuel on hand to win the war.

We’ve covered a variety of operations and inventions that helped the Allies as they invaded Normandy. You can read about Dieppe’s role on amphibious invasions or the Water Buffalo here. No doubt these played crucial roles in securing victory for the Allies. One innovation that is lesser known fueled the Allies as they broke out from Normandy. We mean literally fueled. That operation was Operation PLUTO (pipeline under the ocean). 

It was 1944 and the Allies were gearing up for Operation Overlord. Two years earlier, planners had questioned how they could fuel their military when they chose to invade Europe. One of the largest logistical challenges they would face was fuel supply. The size of their forces - both ground and sky - required enormous supplies of fuel. It was estimated that up to 60% of the total weight of supplies for their invasion forces would be fuel. 

The needs were critical. Moreover, the English Channel was fraught with danger. The Germans had mined the channel, and while the U-boats were not nearly as effective as they were early in the war, they were still ever present. Thus, the leaders deemed the use of fueling tankers too risky and inadequate to meet the needs they expected. 

A groundbreaking idea was put forward. Could the Allies lay a pipeline under the ocean and transport fuel directly from England to the European continent? Nothing like it had been attempted before. The English Channel was notorious for currents and tidal swings that made the body of water very difficult. That’s where Chief Engineer Clifford Hartley came in. 

An Engineering Marvel

Hartley had heard the proposal to use an underwater pipeline. He had seen a pipeline in the hilly terrain of Iran that was three inches in diameter that had successfully delivered fuel. It inspired his idea. He put forward the proposal to use a continuous pipeline (similar to a submarine cable). The pressures the pipeline could handle would enable the Allies to pump aviation fuel and diesel fuel as needed. The plan was well received. It was approved,  code-named Operation PLUTO, and would become one of the most remarkable feats of engineering and logistics of the war. 

Operation PLUTO faced significant technical challenges. For example, they needed to design two different types of pipelines - a pipe that afforded flexibility to navigate an uneven seafloor, but another that could withstand pressures at depths of 100 feet. The two types of pipelines they developed were the HAIS (Hartley-Anglo-Iranian-Siemens) pipe and the HAMEL pipe. The HAIS pipe was lead-coated and provided flexibility. The HAMEL pipe was a steel pipe that helped bolster durability. 

Turning the Tide of the War

The actual laying of the pipeline was its own challenge. Specially designed ships known as “pipelaying vessels” carried out the work. Shortly after D-Day, they set to work. They laid pipelines from the Isle of Wright to Cherbourg to start. They would soon run pipes to various locations along the French coast. 

Operation PLUTO played a crucial role in maintaining the momentum of the Allied advance after the D-Day landings. The pipelines enabled a steady and secure flow of fuel. Fuel was the lifeblood for Allied tanks, trucks, and aircraft. By September 1944, the pipelines were delivering around a million gallons of fuel per day.

PLUTO’s Legacy

Operation PLUTO remains an impressive operation. The Allies’ strategic foresight was one thing, but to execute and deliver was key to supporting the liberation of Europe. As is often the case, winning a war involves more than just military might. 

In the post-war years, the concepts and technologies developed for PLUTO influenced civilian applications, particularly in the field of undersea pipeline construction and maintenance. The legacy of Operation PLUTO, like so many innovations from World War II, extends beyond the war. It highlights the enduring impact of military innovations on peacetime industries.

History for the Hurried:

May 1, 1707: Great Britain was formed from a union between England and Scotland.

May 4, 1494: During his second journey of exploration in the New World, Christopher Columbus discovered Jamaica.

May 5, 1893: The Wall Street Crash of 1893 began as stock prices fell dramatically. By the end of the year, 600 banks closed and several big railroads were in receivership. Another 15,000 businesses went bankrupt amid 20 percent unemployment.