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 Over 170  webpages, 3000 photos, 300,000 visits and 7 million hits each year. The definitive Combined Ops website.

 Please 'like' the Combined Operations Command memorial on Facebook in appreciation of  Allied veterans of WW2.  News and Information at the bottom of this and every webpage.




Pykrete? Ice ships in the Rockies? The improbable but true story of a top secret WW2 project to build ships from a mixture of ice and sawdust. Project Habakkuk! Behold ye among the heathen, and regard and wonder marvellously: for I will work a work in your days, which ye will not believe, though it be told to you. So reads a biblical quotation from the book of Habakkuk ... a name adopted by the top secret project to build ice ships.

Background The Trials Further Reading Acknowledgments


In 1942 the Allies were already developing plans for the re-occupation of Europe, and Winston Churchill favoured large floating platforms to support the landings. In addition the allies were suffering heavy merchant shipping losses from German U-boats, due, largely, to the limited range of patrolling aircraft and the resulting "mid Atlantic Air Gap." Churchill therefore welcomed the idea of building large ships made of ice as presented to him by Lord Louis Mountbatten, 

Mountbatten was Chief of Combined Operations, an organisation responsible to the Chiefs of Staff for the development of equipment and special craft for offensive operations. One of his scientific advisers, Geoffrey Pyke, presented the idea of constructing "berg-ships" - up to 4,000 feet long, 600 feet wide and 130 feet in depth – that could be made cheaply, and in great numbers, from ice. The ships would be insulated and cooled, made practically invulnerable to bombs or torpedoes. They could be used by aircraft to provide protection for shipping, particularly in the mid Atlantic, and as a base for invasion. With Winston Churchill’s enthusiastic endorsement, the project got underway.

In early 1943 two American professors discovered that a very tough material could be produced by adding a small amount of wood pulp to water before freezing. They called this material pykrete, in honour of Geoffrey Pyke.

Lord Mountbatten had a block of Pykrete prepared by a Canadian engineering company and took it to the Quebec Conference in the fall of 1943. As it appeared that "Habakkuk" would run into supply and technical problems, not to mention the high costs ($100 million for the first ship), it was Mountbatten’s aim to get the Americans to take over the project. What better way than to set up a live demonstration! It is reported that he took out his revolver and fired at a block of ordinary ice which immediately shattered. He then fired at a similar block of Pykrete which was so strong that the bullet ricocheted, narrowly missing Sir Charles
Portal the Chief of the Air Staff!

The Trials

Studies commenced into the two paradoxical elements of ice – plastic flow and brittleness. One such study involved the construction of a structure, 60 long by 30 feet wide and 19.5 feet high on a lake in the Canadian Rocky Mountains - Patricia Lake in Jasper, Alberta.

The structure was of wood frame construction with 3 inch x 6 inch studs and 3 inch x 8 inch floor joists and was filled with ice cut from the lake. The structure was insulated and included 3 Freon compressors driven by 10 hp electric motors. Cold air was distributed throughout the ice by a network of 6 inch galvanized-iron cooling pipes. This study was to determine problems of construction and thermal behaviour of ice in summer.

A further experiment was conducted simultaneously in front of the Chateau Lake Louise, near Banff, Alberta. The requirement of this project was to determine ways to reinforce large ice units. The work at Lake Louise indicated that a hull at least 35 feet thick, would be needed to contain damage from bombs and torpedoes.

By this time the Battle of the Atlantic had been virtually won and new aircraft carrier construction was promising to further strengthen defences. Reluctantly the project was shelved.

The floating structure in Patricia Lake in Jasper was abandoned at the end of August 1943. After removing all machinery, and left to sink in place. In the 1970’s scuba divers discovered the remains and they were subsequently studied by the Archaeology Department of the University of Calgary. (Photos left; Work in progress on Patricia Lake, Jasper, Alberta, Canada. Circa 1943  courtesy of the National Research Council of Canada.)

In 1988, the Underwater Archaeological Society of Alberta marked the site with an underwater monument. The following year, with the assistance of the National Research Council and the National Parks branch a plaque, commemorating these unusual wartime events,. was erected on the shore of the lake. (Photo above right July 2001)

Further Reading

There are around 300 books listed on our 'Combined Operations Books' page which can be purchased on-line from the Advanced Book Exchange (ABE) whose search banner checks the shelves of thousands of book shops world-wide. Type in or copy and paste the title of your choice or use the 'keyword' box for book suggestions. There's no obligation to buy, no registration and no passwords. Click 'Books' for more information.

Elsewhere on this site - Geoffrey Pyke 1894 - 1948

Find out about the properties of Pykrete including photographs of blocks subjected to gunfire.

Imperial War Museum, Lambeth Walk, London - books available:-

The Past has Another Pattern memoirs by George W. Ball 1982 ISBN 0-393-01481-9

Pyke: the Unknown Genius David Lampe 1959 (no ISBN given?)

The Challenge of War: Scientific and Engineering Contributions to World War II  Guy Hartcup 1970 ISBN 0-7153-4789-6

"Scientists at War" Wilfred Eggleston 1950   (no ISBN given)

Canadian War Museum- books available:-

No Day Long Enough  George R. Lindsey. Canadian Institute of Strategic Studies 1997

Scientists at War  Wilfred Eggleston 1950.

I wish I'd made you angry earlier - Essays on Science and Scientists by Max Perutz. The essay that discusses the development of Pykrete is entitled 'Enemy Alien'. A fantastic read written by one of the greatest scientists ever. ISBN:0879696745.

Butter Side Up: Delights of Science by Magnus Pyke (ISBN: 0330253093 / 0-330-25309-3) This book was written by Geoffrey Pyke's first cousin and includes a chapter on Pykrete. Copies available on line through ABE Books - see book icon above.


Written by George H Pitt, Alberta, Canada.

If you have any information or book recommendations about Pykrete to add to this page please contact us.


News & Information


Please 'like' the Combined Operations Command memorial  Facebook page in appreciation of our WW2 veterans. See the 'slide shows' of the dedication ceremony and the construction of the memorial plus the 'On this day in 194?' feature where major Combined Ops events are highlighted on their anniversary dates with links to additional information. Also posts and questions from visitors.

The Salvage and Restoration of LCT 7074. This important part of the UK's naval history is to be saved for the nation. It has been raised from the docks at Birkenhead and transported to Portsmouth where restoration work will be undertaken with the aim of revealing it to the public during the 75th anniversary year of D-Day. Google 'LCT 7074' or visit the BBC at for more information.

Forthcoming Events

To organisers; Reach the people who will be interested to know about your Combined Operations or war related event by adding it to our forthcoming events page free of charge.

To everyone else; Visit our forthcoming events page for things to see and places to visit. If you know of an event of possible interest, that is not listed, please let us know.

To notify an event click here.

To visit the webpage click here.

Raffle of a  Painting “Let's Play, not Slay" by David A Thorp depicting the legendary football match between the opposing forces in no man's land on Christmas eve 1914.

The painting has a value of £2,500 and will be raffled during the summer of 2015 in aid of the Royal British Legion and the Cheshire Regimental Benevolent Fund.

Tickets costing £2.50 will be sold at the Cheshire County Show, Tabley  (23 & 24 June), the Royal Welsh Show at Builth Wells, Powys  (20 to 23 July), the Nantwich Show  (July 30) in  Cheshire and the Cheshire Country Game Fair at Tabley (August 29 - 31) where the draw will take place. There will be three further prizes.

Free WW1 Teaching Resource. Newspaper cuttings in the form of a 13 page booklet (26 sides) with published accounts of aspects of the war during 1914 to 1919. Available to schools, universities, libraries and accredited education establishments.  Pdf version or for printed version.

WW2 Combined Operations Handbook. This handbook was prepared for Combined Operations in the Far East. It illustrates the depth and complexity of the planning process necessary to ensure that the 3 services worked together as a unified force.


Thames River Cruiser FARMAR. Do you know what this craft did in WW2? If so you may have information to help a restoration project. More information on our Notice Board.

Find Books of Interest.  Search for Books direct from our Books page. Don't have the name of a book in mind? Just type in a keyword to get a list of possibilities... and if you want to purchase you can do so on line through the Advanced Book Exchange (ABE). 5% commission goes into the memorial fund.

The Gazelle Helicopter Squadron Display Team. The Gazelle Squadron is a unique team of ex-British Military Gazelle helicopters in their original military colours and with their original military registrations. The core team includes four Gazelles, one from each service; The Royal Navy, The Royal Marines, The Army Air Corps and The Royal Air Force. A fifth Gazelle in Royal Marines colours will provide intimate support for the team. Their crest includes the Combined Operations badge. The last, and possibly, only time the badge was seen on an aircraft was in the early mid 40s. A photo of the Hurricane concerned is included in the 516 Squadron webpage.

Newsletter. The latest occasional newsletter can now be read here.

Legasee Film Archive. As part of an exciting social history project, the film company Legasee is looking for veterans from any conflict who would like to have their stories filmed for posterity. Films are now available on line.

New to Combined Ops? Visit Combined Operations Explained for an easy introduction to the subject.

Legion d’Honneur Applications.

Any veterans, not only troops that landed, but also Royal Navy and Royal Air Force personnel who operated in support of the landings may apply. Click here for application form and further information from the MOD.

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Remember a Veteran. Add names to our Roll of Honour and They Also Served pages and read the Combined Operations prayer.

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