He enlisted for naval flight training in May 1942 and earned his wings and a Marine Corps commission as a second lieutenant on February 19, 1943, in Corpus Christi, Texas.

First Lieutenant Hanson arrived in the South Pacific in June 1943 and his daring tactics and total disregard for death soon became well known.

He was commended in the citation accompanying the Medal of Honor for his bold attack against six enemy torpedo bombers, November 1, 1943, over Bougainville Island, and for bringing down four Zeros, the premier Japanese fighter, while fighting them alone over New Britain, January 24, 1944.

Bringing his plane down on the ocean, he paddled for six hours in a rubber life raft before being rescued by the USS Sigourney (DD-643).

He was last seen on February 3, 1944, when his plane crashed into the sea after a cancelled (due to overcast) fighter sweep mission over Rabaul, New Britain.