Ah well, average age.....sort of hard to determine, but there are several numbers one can look at....Let's start with two.
The size of the U.S. Army in 1945 was 8.3 Million. Current size is limited to 548 Thousand (this is by law). Those are important numbers to consider since, in a rapid expansion, one cannot go DOWN in terms of acceptable age for service....one can only go UP. So you would think the average age for COL (O6) would be higher in WWII. But, not so fast....let's take a look at people you should be familiar with and their age at service:
MAJ Richard Winters of "Band of Brothers" fame was 26.
His Commander, COL Robert Sink was 38.
He was ancient compared to Brigadier General Jim Gavin who pinned on his star at 37.
Ensign George H. Bush was 18 (turned 19 just 3 days after his commission).
COL Paul Tibbetts was 30 when he flew the Enola Gay over Hiroshima.
Audie Murphy received his battlefield commission to 2LT at age 20, after almost two years of straight combat service.
Greg "Pappy" Boyington was 31 when he was promoted to Major and given command of his famous "Black Sheep" squadron. His nickname dates from his service with the AVG, where he was considerably older than the other pilots. He was not promoted again (to LTC) until late 1945 because he was declared MIA after being shot down and never documented as a POW until after the war. Pappy was also half Sioux Indian...something that lots of people don't realize.
So, even with a large population of older soldiers, promotions came fast during the war and the average age of an COL would have been around 38. If you go out and try and research it you will find some sources that put it a year or two higher, some a year or two lower. I feel good with 38. Note that Army Air Corps and later USAAF averages are much lower for ages since their promotion rate was accelerated. Drop at least 6 years off that number.
Point on Hollywood. In every movie or serial you see, the actors will be much older than the characters they are playing. MAJ Winters was played in excellent fashion by Damien Lewis, and he was actually pretty close, being only 4 years older than Winters character at the time we're concerned with. Dale Dye, who played COL Sink, was over 30 years older than his character, so he's sort of the other extreme (the actor and USMC vet Dye was the inspiration in real life for the character "Joker" in "Full Metal Jacket"....not a lot of people know that). Audie Murphy played himself in "To Hell and Back", -- he was a full 11 years older by that time. Bob Crane was 37 when "Hogan's Hero's" pemiered, so he sort of matches age with the Army average, but then again, he's too old for a USAAF character.
Average time to promote to O6 in the U.S. Army today is 24 for Active Duty. That makes you about 43. There's been considerable acceleration at lower ranks due to the war (make Captain very quick, but you'll be a Captain a LONG time)
