On April 18, Lieutenant Barber figured prominently in the Yamamoto interception, also known as Operation Vengeance. Intelligence sources had learned that Yamamoto would be flying in a "Betty" bomber on an inspection tour of Japanese bases in the northern Solomon Islands. Historian Donald P. Bourgeois credits Barber with the sole kill of Yamamoto's aircraft. In 1991, Barber and Captain Thomas George Lanphier, Jr. were officially credited with half a kill each in Yamamoto's bomber after the Air Force reviewed the incident. Barber also shared a second Betty destroyed on the same mission. In 2003, Barber was credited by the Governor and Legislature of Oregon with the sole kill after an inspection analyzed the crash site and determined the path of the bullet impacts, thereby validating Barber's account and invalidating Lanphier's claim. However, despite numerous appeals, the US Air Force refused to reverse its 1991 ruling giving each pilot half credit for the kill.