In July 1941, Olander enlisted in the United States Navy as an aviator. He later transferred to the United States Marine Corps Aviation. He served in Col. Pappy Boyington's Black Sheep Squadron. During the Bougainville Campaign, Olander shot down three Japanese planes and was awarded the Distinguished Flying Cross. On December 30, 1943, he became an ace by shooting down his fifth plane in a strike on Rabaul. He left the service with the rank of captain.