If you are interested in Catch-22 and Joseph Heller's experiences in the 340th Bomb Group, I would propose that you read my essay on Catch-22.
Spoiler alert: Heller didn't make anything up. Nearly every event in the novel actually happened, and nearly every character in the novel lived and breathed and walked the sandy beaches of Corsica in 1944.
Take a look:
http://dansetzer.us/heller_index.htm