Via Ultra intercepts, the Allies also detected increased diplomatic and military traffic, which was taken as evidence that the Japanese were preparing an "all-out banzai attack." President Truman ordered a resumption of attacks against Japan at maximum intensity "so as to impress Japanese officials that we mean business and are serious in getting them to accept our peace proposals without delay." In the largest and longest bombing raid of the Pacific War, more than 400 B-29s attacked Japan during daylight on August 14, and more than 300 that night. A total of 1,014 aircraft were used with no losses. B-29s from the 315 Bombardment Wing flew to destroy the Nippon Oil Company refinery at Tsuchizaki on the northern tip of Honshū. This was the last operational refinery in the Japan Home Islands, and it produced 67% of their oil. The attacks would continue right through the announcement of the Japanese surrender, and indeed for some time afterwards.