On 1 September 1939, the day
World War II broke out in Europe, Robins became the Assistant Chief of Engineers in charge of the Civil Works Division of the Office of the Chief of Engineers, with the rank of
brigadier general. As such, he was responsible for all engineer construction activities in the United States except for fortifications. In November 1940, responsibility for airbase construction was transferred from the
Quartermaster Corps to the Corps of Engineers. His first move was to drop "civil" from the division's name. By 30 March 1941, Robins had taken over eighty-one projects worth $200 million (equivalent to $ million in ). During the changeover he worked closely with the head of the Construction Division of the Quartermaster Corps, Brigadier General
Brehon B. Somervell. Robins became responsible not just for Air Corps construction, but for designing and building airports for the
Civil Aeronautics Authority. in 1944 The construction program for the
Air Corps soon increased in size, with sixteen new projects added by 1 April 1941. These included four aircraft assembly plants worth $37.2 million (equivalent to $ million in ) and eight pilot training schools in the
Southern and
Southwestern states. In keeping with the standard practice of the Corps of Engineers, Robins concerned himself with matters of policy and administration, leaving the day-to-day task of supervising and managing construction to the division and district engineers. He imposed the work and financial practices on Air Corps projects that had been developed for, and proven successful on, river and harbor projects. Along with Somervell, he arranged for restrictions to be lifted to give the officers in the field the authority to deviate from standard plans. With the prospect of mobilizing and training an enormous army fast approaching, Robins became involved in preparations for the construction of the necessary
cantonments. In March 1941, he became a member of the War Department Facilities Board, which selected sites for ammunition plants. It had been the practice of the Air Corps to accept tracts of land donated by communities, but many of these sites were often poor and challenging from a construction point of view. New procedures were implemented for site selection for airbases, but in practice the Chief of Engineers, Major General
Eugene Reybold, would not accept a site unless Robins approved it. Robins also headed a panel that drastically reduced the standard
cost-plus contract fees for construction and engineer-architect work. In December 1941, the remaining construction functions of the Quartermaster Corps were transferred to the Corps of Engineers. On 7 December, the Japanese
attack on Pearl Harbor brought the United States into the war. Money was now no object; the priority was to expedite construction work. On 17 December, approval was granted for $827,820,000 () and $388,000,000 () for expediting production. Orders soon came in for the construction of massive industrial facilities like the
Lake Ontario Ordnance Works to produce
TNT and the
Wabash River Ordnance Works to produce the new
RDX explosive. On 12 December, Robins suspended regulations requiring bids on materials. and gave the division engineers authority to execute contracts of up to $5 million (equivalent to $ million in ) and districts to make agreements of up to $2 million (equivalent to $ million in ). , under construction in 1942 On 13 December, the Construction Division moved into the
Railroad Retirement Board Building. Robins occupied Somervell's old suite. He retained all of Somervell's branch chiefs and Somerbvell's deputy, Colonel
Wilhelm D. Styer, became his. On 9 March 1942, the
Services of Supply (SOS) was created under Somervell, who was advanced to lieutenant general, and the Corps of Engineers became an operating division of the SOS. Styer became Somervell's chief of staff, and Colonel
Leslie R. Groves, who had headed the Robins's Operations Branch, became his deputy. In June 1942, a new engineer district was created under Colonel
James C. Marshall, which officially became the
Manhattan District on 13 August 1942. Robins directed all other districts to give Marshall priority for any surplus personnel they might have. On 23 September, Groves became the director of the Development of Substitute Materials project, which became better known as the Manhattan Project, although Groves remained Robins's deputy until mid-1943. Robins expressed his sympathy. He scoured the Corps for personnel, equipment and supplies for the new district, and was involved in authorizing the acquisition of land for the
Clinton Engineer Works in
Tennessee, the
Hanford Engineer Works in
Washington state, and
Project Y in
New Mexico. Robins became the Deputy Chief of Engineers on 1 November 1943. He reached the mandatory retirement age of 64 in March 1945, and retired from the Army with his substantive rank of brigadier general at the end of the month, although he remained on active duty with the temporary rank of major general until 31 December. He was awarded a bronze
oak leaf cluster to his Distinguished Service Medal "for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility as Deputy Chief Engineer from 1943 to 1945." On 16 March 1948, he was promoted to major general on the retired list. ==Death==