On August 20, LeMay arrived to breathe new energy into the XX Bomber Command. The former Eighth Air Force group and wing commander had achieved remarkable success with strategic bombing operations in Europe, testing new concepts such as stagger formations, the combat box, and straight-and-level bombing runs. The youngest two-star general in the Army Air Forces had also revised tactics, tightened and expanded formations, and enhanced training for greater bombing precision. He inaugurated a lead-crew training school so that formations could learn to drop as a unit on cue from the aircraft designated as the lead ship.