Catch-22 tells the story of Yossarian, a bombardier with the US Army Air Corps during WWII. Yossarian becomes convinced that the military will never let him go home as they keep raising the required number of missions – so he seeks another way out. In 2011, we finally found my grandfather’s war diary; this was the diary my father always said I should compare to Catch-22. What followed was years of research and a realization that Papa Julie’s World War II story was known by millions, but somehow eluded those of us closest to him.

When asked about how he conceived of Catch-22, Heller mostly stuck to a similar answer as he gave George Plimpton when interviewed by the Paris Review in 1974:
“I was lying in bed in my four-room apartment on the West Side when suddenly this line came to me: “It was love at first sight. The first time he saw the chaplain, Someone fell madly in love with him.” I didn’t have the name Yossarian. The chaplain wasn’t necessarily an army chaplain—he could have been a prison chaplain. But as soon as the opening sentence was available, the book began to evolve clearly in my mind—even most of the particulars . . . the tone, the form, many of the characters, including some I eventually couldn’t use. All of this took place within an hour and a half. It got me so excited that I did what the cliché says you’re supposed to do: I jumped out of bed and paced the floor. That morning I went to my job at the advertising agency and wrote out the first chapter in longhand. Before the end of the week I had typed it out and sent it to Candida Donadio, my agent. One year later, after much planning, I began chapter two.”
Joseph Heller in interview with George Plimpton, The Paris Review (Issue 60, Winter 2974)
https://www.theparisreview.org/interviews/3894/joseph-heller-the-art-of-fiction-no-51-joseph-heller