Van Kirk served as the navigator for a crew of 12 aboard the Enola Gay, helping to guide the aircraft to Hiroshima on August 6, 1945. The city was home to 250,000 people, as well as an important army headquarters.
He had a lot on his mind the day before the mission. When their superiors advised them to get some rest after one of their last briefings, Van Kirk played poker with his crew mates instead. "How they expected to tell you you were going out and dropping the first atomic bomb and it might blow up the airplane and go get some sleep, is absolutely beyond me," Van Kirk said in a video interview with the Witness to War Foundation.