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Project Habakkuk Breaks the Ice at the Quebec Conference

In the summer of 1943, the Combined Chiefs of Staff of the United States and Great Britain had reached a strategic impasse. To break it, President Franklin D. Roosevelt, British Prime Minister Winston S. Churchill and the Combined Chiefs of Staff, led by U.S. Army Chief of Staff Gen. George C. Marshall and Chief of the Imperial General Staff Field Marshal Sir Alan Brooke, arrived in August at the plush Château Frontenac Hotel in Quebec, Canada, for a conference codenamed Quadrant. When Quadrant ended, agreements on every outstanding issue were reached – but not before gunfire erupted because of one of the most unusual projects of the war, a fleet aircraft carrier made of ice.

Called Project Habakkuk, it was the brainchild of Geoffrey Pyke, director of Programs for Combined Operations under Adm. Lord Louis Mountbatten. He developed it in response to the problem of providing Atlantic convoys aircraft protection against U-boat attack at a time when steel and aluminum production were in short supply. The 2,000-foot long carriers would be made of 1.7 million tons of a special mixture of frozen seawater and wood pulp called “Pykrete,” after its inventor. Pyke composed an “eyes only” memorandum and sent it to his boss, Mountbatten. Mountbatten, an imaginative and at times unconventional thinker, liked the idea and presented it to Churchill, who approved development. Mountbatten ordered a pykrete block sample prepared for a demonstration during Quadrant.

Quadrant Conference

Attendees at the Quadrant Conference in Quebec, Canada. From left to right: (Seated) Prime Minister Mackenzie King of Canada, President Franklin D. Roosevelt, British Prime Minister Winston S. Churchill. Standing: Gen. Henry “Hap” Arnold, Air Chief Marshal Charles Portal, Field Marshal Sir Alan Brooke, Adm. Ernest J. King, Field Marshal Sir John Dill, Gen. George C. Marshall, Adm. Sir Dudley Pound, and Adm. William Leahy. Library of Congress photo

That demonstration almost didn’t happen. The conference opened in a spirit of acrimony and accusation that completely belied the public statements of harmony and cooperation issued by the two governments. In meeting after meeting, the two sides, particularly Marshall and Alan Brooke, went at it hammer and tongs, with Brooke typically prefacing his remarks with an acidic “I flatly disagree,” and then launching into a commentary so blunt that the normally even-tempered Marshall’s cheeks would flush red with rage. During one meeting, Chief of Naval Operations Adm. Ernest King, an Anglophobe with a fiery temper, got so mad he almost leaned across the conference table to smash his fist into a British face after a particularly offensive exchange.

On Aug. 19, the impasse between the two sides reached a crisis point. The meeting grew so heated that midway through, Alan Brooke suggested to Marshall that they clear the room of the sixty-plus officer assistants so that they could have an “off the record” meeting. Marshall agreed. It was near the end of this highly charged, closed door meeting that Mountbatten went to Alan Brooke and asked for the opportunity to update everyone on Habakkuk and give a demonstration. Alan Brooke then turned to Marshall, who gave his permission.

A drawing, from 1943, shows a cross-section of the proposed aircraft carrier. Wikiemedia image

A drawing, from 1943, shows a cross-section of the proposed aircraft carrier. Wikiemedia image

Mountbatten summoned junior officers, who trundled in carts laden with a large block of ice and pykrete that were set up at the far wall of the room. After a speech that brought everyone up to date on Habakkuk, Mountbatten took an ax that had also been carried in, handed it to U.S. Army Air Forces Gen. Henry “Hap” Arnold, and urged him to have a go at the ice and Pykrete. The purpose was to show the resilient superiority of Pykrete. Arnold’s blow on the ice block knocked a chunk off it. His follow-up swing at the Pykrete rebounded with such force that Arnold wrenched his arm. The Pyrkete was barely chipped.

If the generals and admirals thought the demonstration was over, they were wrong – almost dead wrong. Mountbatten had a reputation for occasionally letting his enthusiasms get the best of him. Such was the case today. Mountbatten pulled out his service revolver and, after the group had assembled behind him, announced he would further prove the indestructibility of Pykrete. He then opened fire first on the ice block, shattering it and showering the group with shards. “There, that is just what I told you,” he said. “Now I shall fire at the block on the right to show the difference.” He took aim at the Pykrete and pulled the trigger. According to Field Marshal Sir Alan Brooke’s diary, “the bullet rebounded out of the block and buzzed round our legs like an angry bee.” After grazing King’s leg, the bullet is said to have buried itself in a wall. Fortunately, no one was killed or badly wounded.

A 1946 artist's impression of the proposed HMS Habbakuk. Credit: Illustrated London News Ltd/Mar

A 1946 artist’s impression of the proposed HMS Habbakuk. This illustration clearly shows how the Habbakuk would dwarf other aircraft carriers. Credit: Illustrated London News Ltd/Mar

The aides, meanwhile, were all assembled outside the thick wooden doors of the conference room and well within earshot. When they heard the gunfire, one shouted, “First they argue, then they begin hitting each other, now they’ve started shooting!” On bursting through the door, however, they found a roomful of ice chips and laughing generals and admirals.

New bases and aircraft, improved shipbuilding and other developments soon rendered Habakkuk obsolete and a footnote in World War II history – but one with an unusually distinctive moment in its development.

This story was originally published on September 10, 2010. Inline images were added on December 10, 2021. 


DWIGHT JON ZIMMERMAN is a bestselling and award-winning author, radio host, and president of the...

    li class="comment even thread-even depth-1" id="comment-299">
    Armando J. Heredia

    It’s fortunate that the U-boat threat was finally diminished such that Habakkuk did not need to be built. As many historical observers have noted, the refrigeration plant and ducting alone required to keep a Pykrete carrier “intact” would have consumed an equally critical amount of materials and manpower that could be applied to building conventional combatants. At 7 knots, it would have been a very slow moving platform. Operationally speaking, I cannot imagine how it would fare in a CONFLAG scenario, given the amounts of munitions and avgas it would have stored on-board to support the aviation component.

    li class="comment odd alt thread-odd thread-alt depth-1" id="comment-300">
    Chuck Oldham (Editor)

    I suppose with the sheer size, you don’t have to worry about having 25 knots of wind over the deck for launch and recovery. Certainly it was one of those ideas that seems brilliant on its face, but collapses quickly as the details have to be worked out.

    li class="comment even thread-even depth-1" id="comment-301">
    Dwight Zimmerman

    It also speaks to how great the U-boat danger was at the time that such a concept got as far as it did.