John Thomason was an artist and writer in the early 20th Century. The Marine Corps was his subject. His knowledge was based on his experiences in WWI and his overseas service in the ’20s and ’30s. Wiki has a short bio and a list of titles. It misses how popular and widely read his work was.
Back in 1993, American Heritage Magazine had a long biographical article about him. It is now available online. Here’s a quote from the end of it.
John W. Thomason was the prototype of a vanished Marine Corps era; the Old Breed survived from the First World War until it was submerged by the hordes of new recruits in the Second. He was a hugely competent writer, if not from the top literary drawer, at the very top of the second. His characters were neither complex nor deep (with the possible exception of Praxiteles Swan), but they were alive, men (and women) of action, with no forced macho overtones, and their dialogue was vivid and rang true; for all his physical problems, Thomason never suffered from a tin ear.
His prose, moreover, is unique; he shares with Rudyard Kipling and H. H. Munro (Saki) the distinction of having stamped his identity on every paragraph. Nothing he wrote could ever be mistaken for anyone else’s work. His writing was lean and muscular (not always a favorite adjective with current critics), but it was also sensitive, and it carried his stories buoyantly, with never a word wasted. His values were clean and clear-cut; those aspiring to acquire the elements of literary style can do far worse than turning to his pages. His illustrations were equally unique; his simplest sketch can’t be confused with that of any other artist.
Few remember him now (there are, astonishingly, even Marines who can’t identify him), but for decades he stood for the Marine Corps, for the Old Corps and its old values, and for high adventure in distant and exotic climes.
And here’s an example of his sketches.