with graduates of Army Air Forces Training Command schools to become effective combat units. The OTU program was patterned after the unit training system of the Royal Air Force. Phase I training concentrated on individual training in crewmember specialties. Phase II training emphasized the coordination for the crew to act as a team. The final phase concentrated on operation as a unit. By late 1943 most of the Army Air Forces (AAF)'s units had been activated and almost three quarters of them had deployed overseas. With the exception of special programs, like forming Boeing B-29 Superfortress units, training “fillers” for existing units became more important than unit training. The squadron mission changed to that of a Replacement Training Unit (RTU). The RTU was also an oversized unit, but its mission was to train individual pilots or aircrews. However, the AAF was finding that standard military units like the 60th, whose manning was based on relatively inflexible tables of organization were proving not well adapted to the training mission, even more so to the replacement mission. Accordingly, the Army Air Forces adopted a more functional system in which each base was organized into a separate numbered unit. Most of the OTUs and RTUs were inactivated or disbanded and training activities given to these base units. The 39th Group and its components were inactivated, and along with supporting units at Davis-Monthan, replaced by the 233rd AAF Base Unit (Combat Crew Training School, Bombardment, Heavy). B-29 Superfortress operations against Japan The 39th Group and its squadrons, including the 60th, were activated the same day at Smoky Hill Army Air Field, Kansas as B-29 Superfortress units. When training was completed moved to North Field Guam in the Mariana Islands of the Central Pacific Area in January 1945 and assigned to XXI Bomber Command, Twentieth Air Force. Its mission was the strategic bombardment of the Japanese Home Islands and the destruction of its war-making capability. Flew "shakedown" missions against Japanese targets on Moen Island, Truk, and other points in the Carolines and Marianas. The squadron began combat missions over Japan on 25 February 1945 with a firebombing mission over Northeast Tokyo. The squadron continued to participate in wide area firebombing attack, but the first ten-day blitz resulting in the Army Air Forces running out of incendiary bombs. Until then the squadron flew conventional strategic bombing missions using high explosive bombs. The squadron continued attacking urban