How did Roald Dahl become an author?

During World War II, Roald Dahl was a fighter pilot. After he was sidelined by severe headaches in 1941, Roald was transferred to Washington, DC where C.S. Forester encouraged Roald to write about his experiences in the Royal Air Force (RAF).

That writing, Dahl's first published work, appeared in the 1 August 1942 issue of The Saturday Evening Post, and was titled "Shot Down Over Libya".