During the Guadalcanal Campaign Admiral Halsey USN made a tour of the front lines that was a great morale booster. Admiral Yamamoto IJN decided to do a similar tour of forward basis. Due to U.S. code breaking activities and Ultra, Yamamoto's itinerary was determined. Both the U.S. Army Air Force and U.S. Navy stepped up air attacks generally to cover the assassination mission, and a group of P-38s were purposefully sortied to intercept the two aircraft carrying Yamamoto and his staff. The Army mission was a success and both aircraft were shot down and all, including Yamamoto, were killed. In some respects the killing of Yamamoto was a mistake, and of course could not be publicized until the Japanese announced it, because it may have compromised that the Japanese code had been broken.