The 1st Bombardment Wing, commanded by Brigadier General Robert B. Williams, was made up of nine B-17 groups. Previously, because of this large number of groups, "provisional combat bomb wings" had been formed in April to control the groups tactically during large missions. To achieve a "maximum effort" against Schweinfurt, the 1st Bomb Wing, with sufficient aircraft and crews to employ four wing-sized boxes, formed provisional groups as well as wings, accomplished by eight groups providing a squadron or spare aircraft to form the "composite groups" needed to form a fourth combat wing. The Schweinfurt force in all had 230 bombers comprising 12 groups divided into two task forces, each with two wings, each wing composed of a three group formation, and was more than twenty miles in length. Williams personally led the mission, flying as co-pilot in an aircraft of the lead formation, as wingman to the commander of the 91st Bomb Group.