The primary target for the August 9 bombing mission was the industrial city of Kokura. Hence, Bock and his crew flew The Great Artiste in a support role on the mission and Sweeney and his crew, aboard Bockscar, became the primary unit to drop the second atomic bomb on Japan. However, when the mission date moved forward, it did not give the ground crews enough time to do the transfer, so it was decided that Sweeney and Bock would switch planes. Sweeney and his crew had been doing training runs in Captain Bock’s plane Bockscar while The Great Artiste was to have its instruments removed and installed in another plane. The next mission was planned for August 11 but due to a poor weather forecast, the commanders decided to move the attack up by two days, setting a new date of August 9. Upon their return Sweeney and his crew began to prepare for their turn. Sweeney and his crew C-15 had previously flown The Great Artiste with the Enola Gay on her flight to Hiroshima on August 6, carrying instrumentation to record and support the mission. Sweeney was the plane scheduled to drop the second atomic bomb. Originally, The Great Artiste commanded by Major Charles W.
Bock who, along with his crew C-13, participated in several bombing runs on Japan prior to the events that occurred in early August, 1945. It was named after its commander Captain Frederick C. Bockscar was part of the same squadron as the Enola Gay, the 393d Bombardment Squadron, Heavy, of the 509th Composite Group (USAAF).