Ketcham started in the business as an animator for Walter Lantz and eventually Walt Disney, where he worked on Fantasia, Bambi and Pinocchio. During World War II, Ketcham was a photographic specialist with the US Navy Reserve. Also while in the Navy he began a camp newspaper strip. Half Hitch, which ran in The Saturday Evening Post beginning in 1943.
I wonder if Dennis was modeled after a Sailor he knew. I could think of several.