On 26 October 1942, Oliphant embarked from Melbourne, taking Rosa and the children back with him. The wartime sea voyage on the French Desirade was again a slow one, and they did not reach Glasgow until 28 February 1943. He had to leave them behind once more in November 1943 after the British Tube Alloys effort was merged with the American Manhattan Project by the Quebec Agreement, and he left for the United States as part of the British Mission. Oliphant was one of the scientists whose services the Americans were most eager to secure. Oppenheimer, who was now the director of the Los Alamos Laboratory attempted to persuade him to join the team there, but Oliphant preferred to head a team assisting his friend Lawrence at the Radiation Laboratory in Berkeley to develop the electromagnetic uranium enrichment—a vital but less overtly military part of the project.
