In early 1942 the German war machine was engaged in a deadly race against the Allies to build the world’s first atomic bomb. Central to this effort was the remote experimental plant at Vemork in occupied Norway, where heavy water, an essential element in the development of nuclear weaponry, was under production. The Allies had considered trying to bomb the plant, but decided that the risks of widespread contamination and loss of civilian life were too great. Instead they resorted to sabotage. After a couple of failed operations, in late February a crack team of British and Norwegian commandos overcame freezing temperatures, hostile terrain and limited German security to place a number of explosives at the heart of the Vemork base. The results were devastating. More than half a ton of the heavy water manufactured since the occupation of Norway was destroyed, while a range of valuable equipment was lost too. The Germans also had to divert over 3,000 troops to protect the plant from further attack. Their cherished bomb was never built.