Thomas Farrell ( general ) Major General Thomas Francis Farrell ( 3 December 1891 – 11 April 1967 ) was the Deputy Commanding General and Chief of Field Operations of the Manhattan Project , acting as executive officer to General Leslie R . Groves , Jr . Farrell graduated from Rensselaer Polytechnic Institute with a degree in civil engineering in 1912 . During World War I , he served with the 1st Engineers on the Western Front , and was awarded the Distinguished Service Cross and the French Croix de guerre . After the war , he was an instructor at the Engineer School , and then at the United States Military Academy at West Point . He resigned from the Regular Army in 1926 to become Commissioner of Canals and Waterway for the State of New York from 1926 to 1930 , and head of construction and engineering of the New York State Department of Public Works from 1930 until 1941 . During World War II he returned to active duty as Groves ' executive officer in the Operations Branch of the Construction Division under the Office of the Quartermaster General . He went to the China - Burma - India theater to help build the Ledo Road . In January 1945 , Groves chose Farrell as his second - in - command of the Manhattan Project . Farrell 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 . In 1946 he was appointed chairman of the New York City Housing Authority . He subsequently worked as a consultant for the Triborough Bridge and Tunnel Authority on projects such as the Cross Bronx Expressway . He was a member of the evaluation board for Operation Crossroads , and was an advisor to Bernard Baruch , the United States representative on the United Nations Atomic Energy Commission . During the Korean War , Farrell returned to active duty once more , serving with the Defense Production Administration , and then with the Atomic Energy Commission as its Assistant General Manager for Manufacturing . He oversaw a vast increase in the Commission ' s production capabilities before retiring again in 1951 . From 1960 to 1964 , he worked on the preparations for the 1964 New York World ' s Fair . Early life . Thomas Francis Farrell was born on 3 December 1891 in Brunswick , New York , the fourth of nine children of John Joseph Farrell , Sr . , a farmer , and his wife Margaret née Connolly . Farrell was raised on the family ' s farm , where his father had an apple orchard , and raised pigs and dairy cattle . The children helped with the farm chores , and delivering the milk , but none stayed on as adults . Farrell graduated from Rensselaer Polytechnic Institute in 1912 . His first professional job was working on the New York State Barge Canal . Seeing Irish workers being mistreated by bosses made him a staunch supporter of organized labor . He worked on the Panama Canal from 1913 to 1916 . Farrell joined the Corps of Engineers Officers Reserve Corps in 1916 . He married Maria Ynez White in 1917 before departing for France with the American Expeditionary Force ( AEF ) . He joined the 1st Engineers with the rank of second lieutenant , and departed from Hoboken , New Jersey on the USAT " Finland " on 6 August as the assistant supply officer with the rank of first lieutenant . He became a captain and regimental supply officer in October , and subsequently , with the rank of major , commanded the 2nd Battalion from January to May 1918 , Company F from May to July , and finally the 1st Battalion from July 1918 . Farrell participated in the Battle of Cantigny , the Aisne - Marne Offensive , the Battle of Montdidier - Noyon and the Meuse - Argonne Offensive . The 1st Engineers ' main role was maintenance of the roads and construction of bridges in the 1st Division area , although detachments also employed Bangalore torpedo es to clear paths through barbed wire . However , during the Argonne battle , Farrell ' s 1st Battalion was committed to the line as infantry . For his leadership in the action that followed , he was awarded the Distinguished Service Cross . His citation read : Farrell was also awarded the Croix de guerre with palm for his actions , and the 1st Battalion received a citation from Major General Charles Summerall , the commander of V Corps . After the Armistice with Germany in November 1918 , the 1st Engineers participated in the occupation of the Rhineland , with Farrell ' s 1st Battalion basing itself at Ebernhahn . The 1st Engineers returned to the United States in August and September 1919 . After the war , Farrell joined the Regular Army . He served as an instructor at the Engineer School at Camp A . A . Humphreys from 1921 to 1924 , and then at the United States Military Academy at West Point until 1926 . Farrell resigned from the Regular Army in 1926 , but remained in the reserves . The Governor of New York , Al Smith , appointed Farrell as Commissioner of Canals and Waterway for the State of New York . He was head of construction and engineering of the New York State Department of Public Works from 1930 until 1941 . He was considered as a possible candidate to replace Frederick Stuart Greene as Superintendent of Public Works , but Greene did not retire . The Great Depression led to a vast expansion of public works activity , both nationally and in New York . Major projects in New York included the 1939 New York World ' s Fair and the construction of LaGuardia Airport . World War II . Construction in the United States . Farrell returned to active duty in February 1941 with the rank of lieutenant colonel to act as then - Colonel Leslie R . Groves , Jr . ' s executive officer in the Operations Branch of the Construction Division under the Office of the Office of the Quartermaster General . At this point , the US Army was about to embark on a national mobilization , and it was the task of the Construction Division of the Quartermaster Corps to prepare the necessary accommodations and training facilities for the vast army that would be created . The enormous construction program had been dogged by bottlenecks , shortages , delays , spiralling costs , and poor living conditions at the construction sites . Newspapers began publishing accounts charging the Construction Division with incompetence , ineptitude , and inefficiency . Farrell and Groves worked out new , simplified procedures for centralized procurement that provided the flexibility needed to get projects done on time with the accountability that such enormous expenditures demanded . He was awarded the Legion of Merit for his services . China - Burma - India . In September 1943 , the Chief of Army Service Forces , Lieutenant General Brehon B . Somervell , created a special India Committee to coordinate activities in the China - Burma - India theater with those of Army Service Forces back home . Farrell , now a colonel , was appointed to the committee to oversee construction . The creation of a line of communications from India to China would be the largest engineer undertaking of the war . A number of new units were trained in the United States specifically for the task . In a reorganization later that year , Farrell became Chief Engineer of the Services of Supply in the China - Burma - India theater . In December he also became head of its Construction Division . Farrell , who was promoted to brigadier general in January 1944 , organized his command into two divisions and six districts . He was in charge of the work inside India ; construction of the Ledo Road itself was the responsibility of Colonel Lewis A . Pick . In addition to this work , Farrell had to support Operation Matterhorn , the deployment of B - 29 bombers to China and India , which involved the construction and expansion of a series of air bases . The B - 29s required runways that were almost twice the size of those for the older B - 17 s . He was also forced to divert his resources to construct a oil pipeline to the Matterhorn airfields . To bridge the fast - following rivers of northern Burma , Pick and Farrell selected the H - 20 Portable Steel Highway Bridge . Production of these had been discontinued in favor of the Bailey bridge , but Farrell ' s technical arguments won out and the Corps of Engineers had to reinstate production of the H - 20 . In view of these difficulties , Farrell obtained Bailey bridges from British sources . In the end , all the major bridges beyond the Irrawaddy River would be Baileys . He also made the decision , controversial in Washington , to shift the terminus of the oil pipeline from Calcutta to Chittagong in order to avoid crossing the Ganges and Brahmaputra Rivers , and the dangers of concentrating too many vulnerable installations in the Calcutta area . He was awarded the Distinguished Service Medal . Manhattan Project . In December 1944 , the Secretary of War , Henry L . Stimson , ordered Groves , now the Director of the Manhattan Project , to find a deputy . Stimson was concerned about what would happen if Groves became incapacitated . " You can have any officer in the Army , " Stimson told Groves , " no matter who he is , or what duty he is on . " Groves told Colonel Kenneth Nichols , the commander of the Manhattan District , that his first choice would be Farrell . Nichols replied : " He would be my first choice too . " Farrell was briefed on the physics of the atomic bomb by Robert Oppenheimer , and he made several extended tours of the Alamogordo Bombing and Gunnery Range , which had been chosen as the site for the Trinity test . On signing a receipt for the plutonium from Oak Ridge , Farrell commented : Farrell observed the Trinity Test with Oppenheimer from the control dugout located from the test tower . In his report on the test , Farrell stated : Farrell assumed special responsibility for combat operations . He served on the target committee , acting as its chairman when Groves was absent . In July 1945 , Farrell arrived on Guam to coordinate the project with the local commanders . One of his tasks was to brief General of the Army Douglas MacArthur . Farrell was joined by Rear Admiral William R . Purnell , who represented the Military Liaison Committee , and Captain William S . Parsons , the commander of Project Alberta . They became , informally , the " Tinian Joint Chiefs " , with decision - making authority over the nuclear mission . Farrell notified Groves that the Little Boy bomb would be ready for use on or about 3 August , weather permitting . In the space of a week on Tinian , four B - 29s crashed and burned on the runway . Parsons became very concerned . If a B - 29 crashed with a Little Boy , the fire could cook off the explosive and detonate the weapon , with catastrophic consequences . Parsons raised the possibility of arming the bomb in flight with Farrell , who agreed that it might be a good idea . Farrell asked Parsons if he knew how to do it . " No sir , I don ' t " , Parsons conceded , " but I ' ve got all afternoon to learn . " After the bombing of Hiroshima on 6 August , Farrell , along with Generals Carl Spaatz , Nathan Twining , Barney Giles and James H . Davies , debriefed Parsons , the aircrews and the observers , and sent Groves a detailed report . Farrell brought forward the date for the next attack because good weather was only predicted until 9 August . He signed the Fat Man bomb , " To Hirohito , with love and kisses , T . F . Farrell . " The bomb was loaded on the B - 29 " Bockscar " . During pre - flight inspection , a fuel pump was found to be faulty , meaning that of fuel in the bomb bay tank could not be used , although it would have to be carried . Farrell took the difficult decision to continue the mission , in view of the worsening weather . This was only the first of a number of problems that faced the mission crews that day , but the mission was carried out successfully . The surrender of Japan on 14 August precluded further attacks . Groves had already directed Farrell to prepare teams to inspect the effects of the atomic bombs on Hiroshima and Nagasaki , and Farrell had begun assembling the required personnel and equipment . Farrell arrived in Hiroshima by air on 8 September as part of a group , equipped with portable geiger counter s , that was headed by himself , and also included Brigadier General James B . Newman , Jr from the US Army Air Forces , Japanese Rear Admiral Masao Tsuzuki , who acted as a translator , and Colonel Stafford L . Warren , the head of the Manhattan District ' s Medical Section . They remained in Hiroshima until 14 September and then surveyed Nagasaki from 19 September to 8 October . They were greatly impressed by both the damage done by the atomic bombs , and the extensive Japanese preparations for the Allied invasion that had been planned prior to the surrender . Post - war . Farrell was promoted to the rank of major general in October 1945 . He remained Deputy Commander of the Manhattan Project until he retired from active service in April 1946 . He was appointed chairman of the New York City Housing Authority by Mayor William O ' Dwyer on Robert Moses ' s recommendation . In the aftermath of the war , providing public housing , especially for returning veterans , was a major priority for the city . Unlike other projects of the time , New York City public housing was not racially segregated . Writing in 1950 , Farrell declared , " New York ' s public housing projects demonstrate that Negroes and whites can live together . " He served as a member of the evaluation board for Operation Crossroads , and was an advisor to Bernard Baruch , the United States ' representative on the United Nations Atomic Energy Commission . In 1950 , during the Korean War , Farrell returned to active duty with the Army once more , and served with the Defense Production Administration . In July 1951 , he was transferred to the Atomic Energy Commission ( AEC ) , the successor organization to the Manhattan Project , where he became the Assistant General Manager for Manufacturing . In this role , he oversaw a vast increase in the Commission ' s production capabilities . The construction of new reactors at the Hanford and Savannah River Site s would eventually triple the production of nuclear weapons . Farrell left the AEC and active duty Army again in February 1952 . He subsequently worked as a consultant for the Triborough Bridge and Tunnel Authority on projects such as the Cross Bronx Expressway . From 1960 to 1964 , he worked on the preparations for the 1964 New York World ' s Fair . His children were Thomas , Barbara , Peter , Patricia , and Stephen . Thomas graduated from West Point in the class of 1942 , received the Silver Star Medal and the Distinguished Service Cross , and reached the rank of captain before being killed at Anzio on 25 February 1944 . An Army port repair ship , the USS " Thomas F . Farrell Jr . " , was named in his honor . Peter graduated from West Point in the class of 1950 . He served with the Army in the Vietnam War , where he commanded the 6th Battalion , 56th Air Defense Artillery during the Tet Offensive . He retired from the Army in 1978 with the rank of colonel . Farrell ' s daughter , Barbara Vucanovich , was the first woman from Nevada to be elected to the United States House of Representatives , serving from 1983 to 1997 . His granddaughter , Patricia Dillon Cafferata , served as Nevada State Treasurer from 1983 to 1987 . Farrell died at Saint Mary ' s Hospital in Reno , Nevada , on 11 April 1967 . His wife Ynez had died the year before . Ironically , the man who had spent a lifetime building things was principally remembered for the destruction of Hiroshima and Nagasaki .