In the show ‘The Pacific’, ‘Gunny’ is significantly older than the other US marines and appears to be in his mid to late forties. Was the portrayal of this character accurate? Was it common to find front line combat troops this old in the US military during WWII?

A note to start this off at, Gunnery Sergeant is the modern-day pay grade of E-7, with this rank typically serving as the senior operations NCO for company level formations in the the USMC.

At the Hearings before the.Committee on Naval Affairs of the House of Representatives in 1912 the qualifications and selection of gunnery sergeants was explained in congressional testimony as follows :

A candidate for appointment as gunnery sergeant in the United States Marine Corps should be sufficiently proficient in the drill regulations to thoroughly drill recruits and to drill the squad and company. They should be thoroughly conversant with the nomenclature of the rapid-fire and machine guns used in the naval service and be sufficiently acquainted with their drill to be able to act as gun captains and to instruct the enlisted in their duties at such guns. They should have knowledge of the kinds and quantities of ammunition used in those guns. They should have a thorough knowledge of the instructions pertaining to target practice. They should have sufficient knowledge of the system of accountability of the United States Marine Corps to take charge of and properly render the accounts of a guard aboard ship, and should be competent in all respects to perform the duties of a first sergeant in charge of a guard on ship to which no marine officer is attached; also a knowledge of the duties involved in the subsistence of Marines ordered on detached duty, as well as the duties of an officer in command of a part of a landing party on shore.

Gunnery sergeants are selected from the sergeants of the corps on account of superior intelligence, reliability, and mechanical knowledge. The grade was provided with the idea that they should be somewhat higher in standard than first sergeants; that their knowledge of ordnance and of gunnery should be such that they would be able to make minor repairs to guns—to supervise all work in connection with guns; to command detachments which were of such size as not to warrant a commissioned officer being assigned to them. They are at present in command of marine detachments at naval magazines; are performing duty as first sergeants of regularly organized companies at various posts; in connection with the repair of guns at various Marine Corps stations; in connection with the training of recruits; and, in general, performing duties that require the utmost reliability. For a number of years candidates for promotion to this grade were required to take a special course of instruction before receiving their warrants, but recently, because of the lack of first sergeants and the numerous small detachments organized, it has been necessary to detail many of them for duty as first sergeants. As soon as there are a sufficient number of first sergeants available, it is intended to reestablish the school and to give gunnery sergeants a thorough course of instruction prior to their permanent appointment to this grade, in order that they may be experts in all matters pertaining to the care and preservation of naval ordnance.

All-in-all a very experienced person and that can take years to cultivate said experience.

But surly it doesn’t take that long to get experience, right? Well let us look at the numbers of personnel in the USMC throughout the years. According to the Marine Corps University, the USMC had 52,819 personnel in 1918, 51,316of which were enlisted. Just two years later, in 1920, the USMC was down to 17,165 personnel, of which 16,061 were enlisted. As we can see, that is a substantial drop in personnel. This in turn would make it difficult to get promoted as there can only be X number of soldiers of certain ranks in the military, especially with officers and NCOs. To use an example from the US Army, Dwight D. Eisenhower was commissioned in 1915 and by the end of WWI he was a Lieutenant Colonel but was reverted back to the rank of Captain after the war. He would make Major in 1924 and would remain at that rank until 1936, 12 years. The current expected time to serve as a major is about 6 years +/- a few years based on performance. Eisenhower would only start receiving promotions again once the size of the military increased. So as you can see, drawdown meant stagnation for many who stayed in the military and expansion meant promotion.

So the likely assumption would be that that Gunny was a mid-level NCO for much of the interwar period and with the military expansion of the war, would have been promoted to fill a senior NCO role as the USMC expanded.

Edit: fixed some errors