John Robert Elting was a soldier for thirty-five years (1933-1968), with a couple of civilian interludes as a high school instructor. His first commission had been from the Reserve Officer Training Corps at Stanford University in 1932. He combined this with summer duty in Company H (machine-guns), 163rd Infantry Regiment, Montana National Guard, and then as an officer in the Civilian Conservation Corps. In 1940 he became an ROTC instructor at Oregon State College. From then on he was continually in service until 1947 (71st Armored Field Artillery Battalion, the Tactics Department of the Armored School at Fort Knox, Combat Command B of the 8th Armored Division in the Rhineland, Ardennes, Alsace, and Central Europe campaigns, 24th Field Artillery Battalion of the Philippine Scouts). In 1948 he was recalled, after a short civilian interlude as a teacher, and was assigned to the Armed Forces Information School and, from there, to the Military Academy, West Point.

In 1954 John Elting's turn for overseas duty came up and he was posted to the J-2 (Intelligence) Division of the Far East Command, returning to West Point in 1957. There he began researching and writing A Military History and Atlas of the Napoleonic Wars, with Colonel Esposito acting as overall editor and advisor. Between 1965 and 1968, Colonel Elting served as G-2 of the Washington Military District, before retiring in 1968.

After his retirement, he turned his attention to writing and research (in his own modest words, he 'tried to be a historian'). He was a military consultant to TimeLife Books for the World War II, Civil War, and Third Reich series. He was also the author, co-author or editor of sixteen books, including The Battles of Saratoga, American Army Life, A Dictionary of Soldier Talk, Swords Around a Throne and the four volumes of Napoleonic Uniforms. He took particular delight in the history of Napoleon's Army and the French emperor's campaigns and in the study of the American Revolution, but was a considerable authority on all aspects of military history. His knowledge was deep, and he gave generously of it, and for many he served as an inspiration. After a short illness, he passed away suddenly, seated at his desk in his study, at home, on Thursday 25 May.