Swarthout also began to sell short stories to national publications such as "Cosmopolitan" and "The Saturday Evening Post". He was paid $2500 in 1955 for one of these stories, "A Horse for Mrs. Custer", which became a Randolph Scott low-budget Western for Columbia Pictures in 1956, under the title "7th Cavalry". The day after he finished his last doctoral examination, he started writing a novel called "They Came To Cordura". Its setting was Mexico of 1916 during the Pershing Expedition to capture Pancho Villa, and some of its fictional cavalry troopers had been nominated for Medals of Honor. The book was quickly sold to Random House and then to Columbia Pictures in 1958, becoming one of their major motion pictures starring Gary Cooper and Rita Hayworth a year later. This" NY Times "bestseller and the movie money enabled Swarthout to become a professional writer at last. He was 39 years old.