Development of an actual bomb had been painfully slow, with the work spread out across four universities and enriched uranium sourced in Canada. Finally, in early 1942, a prototype was ready for testing. That’s where Havelock came in, based on his work at Cambridge and his experience pioneering weapons test protocols between the wars. It was his meticulous refinement of wind tunnel development that earned him a visit at Cambridge from Paget Thomson.

But an atomic weapon was something entirely different. Testing had to be not only safe, but also observable and discreet. Havelock’s solution had been to propose a test detonation in a remote atoll, where the weapon’s effects could be viewed from ships anchored at a distance and there would be little chance of discovery by the Germans. Thomson took it up with the Ministry of Defence, who found a reluctant but ultimately willing partner in the Royal Australian Navy. The site would be the uninhabited Monte Bello island chain 120 miles north of the western Australian coast.

The prototype bomb had been loaded onto the Australian Navy destroyer HMAS Vampire in Gibraltar under cover of night and sailed, well escorted, around the Cape of Good Hope to avoid the U-boat infested Mediterranean. The stopover in Ceylon was supposed to be a routine refueling. Unfortunately, it had coincided with the Japanese surprise attack on Trincomalee.

HMS Hermes, the second ship sunk along with the Vampire, was the world’s first purpose-built aircraft carrier, built in 1918 and would have been scrapped if not for the badly stretched Eastern fleet that made use of her flight deck to launch Fairey Swordfish biplanes. Both ships were fleeing Trincomalee harbor ahead of the Japanese attack, but were spotted and quickly pounced upon by a squadron of Mitsubishi A6M Zeros. Hermes took over 40 direct hits and went into a derelict circular limp before succumbing to her wounds and nosing beneath the waves, taking 309 souls with her. Vampire went down mercifully sooner, but with only nine crew aboard. The hospital ship, Vita, picked up survivors, while some managed to swim the eight miles to shore, where they were rescued by surprised villagers.

The Americans, who had suffered their own surprise attack only months earlier at Pearl Harbor, were now in the war and pressuring the British government to collaborate on an atomic “deterrent.” Havelock was vehemently against the idea of sharing secrets with the Americans. He was glad they had joined the war effort, but begrudged them for taking so long while England bore the brunt of the Axis Powers’ fury. He wanted Tube Alloys to remain a purely British endeavor. Call it national pride, call it official secrets—he knew once the Americans got hold of their research, Britain would be reduced to a supporting role. And with the sinking of the Vampire, this looked all the more inevitable.