OPERATION PLUTO

THE ALLIES’ SECRET UNDERWATER WEAPON THAT HELPED DEFEAT THE NAZIS

- JOHN BROICH

ON THE COLD MORNING OF December 29, 1942, HMS Holdfast pitched through the rough waters of the Bristol Channel between the Welsh port of Swansea and the English harbor of Watermouth.

Cable handlers guided a completely new kind of pipe over the stern—mile after mile unreeling into the gray swells below. If the line kinked or snapped under its own weight in the 160-foot depths, months of work would lie broken on the seabed.

This was no ordinary experiment but a full-scale test run for something far bolder: laying a fuel pipeline beneath the English Channel itself.

Eight months before, Arthur Hartley, the chief engineer for the Anglo-Iranian Oil Company, had spotted a map spread open in a Petroleum Department office. It showed the Channel as planners puzzled how to span it with oil pipelines from England to northern France to feed an Allied liberation of Europe, which would demand fuel—rivers of it. This technology, still less than a year old, might be the only way to deliver it. But nothing like it had ever been attempted.

Yet Hartley had gotten an idea, and now, in the final days of 1942, 30 miles of that idea was sinking into the water. The English Channel was far broader and deeper than the Bristol one now tossing the Holdfast, but if this trial worked, the real thing just might succeed, too.

Finally, the Holdfast reached the English side of the Channel. The pipeline never broke, never kinked. The unspooling system held.

About a month later, the Germans attacked Swansea, with one bomb exploding 100 feet from where the pipe began. The line remained undamaged, small but vital proof of its resilience.

More rehearsals would follow: The pipe had to be tested under pressure and joined to pumps and tanks before hundreds of miles of it could be reproduced. The question was whether Britain could be ready in time.