Major General Farrell (right) and Major General Groves, Jr., (left), in 1945. The Manhattan Project was a research and development program by the US with the UK and Canada that produced the first atomic bomb during WWII. Lieutenant General Leslie Richard Groves, Jr. (August 17, 1896 - July 13, 1970) was a US Army Corps of Engineers officer who oversaw the construction of the Pentagon and directed the Manhattan Project. He directed the enormous construction effort, made critical decisions on the various methods of isotope separation, acquired raw materials, directed the collection of military intelligence on the German nuclear energy project and helped select the cities in Japan that were chosen as targets. Major General Thomas Francis Farrell (December 3, 1891 - April 11, 1967) was the Deputy Commanding General and Chief of Field Operations of the Manhattan Project, acting as executive officer to General Groves. He observed the Trinity test at the Alamogordo Bombing and Gunnery Range with J. Robert Oppenheimer. In August 1945, he went to Tinian to supervise the bombing of Hiroshima and Nagasaki. Afterwards he led teams of scientists to inspect the effects of the atomic bombs.