Ten days later, sixty-eight Superfortresses took off at night from staging bases at Chengtu to bomb the Imperial Iron and Steel Works at Yawata on Kyūshū, more than away. The June 15, 1944, mission – the first raid on the Japanese home islands since the Doolittle raid of April 1942 – marked the beginning of the strategic bombardment campaign against Japan. Like the Doolittle attack, it achieved little physical destruction. Only forty-seven of the sixty-eight B–29s airborne hit the target area; four aborted with mechanical problems, four crashed, six jettisoned their bombs because of mechanical difficulties, and others bombed secondary targets or targets of opportunity. Only one B–29 was lost to enemy aircraft over the target, while another was strafed and destroyed by Japanese aircraft after making an emergency landing at Neihsiang.