11,465 of those killed were younger than 20 years old. Of those killed, 17,539 were married. Average age of men killed: 23.1 years Enlisted: 50,274; 22.37 years Officers: 6,598; 28.43 years Warrants: 1,276; 24.73 years E1: 525; 20.34 years Five men killed in Vietnam were only 16 years old.
The Korean War - Statistics & Facts
https://www.statista.com/topics/10172/the-korean-war/#statisticChapter
US MILITARY CASUALTIES IN WORLD WAR II
Branch Killed Wounded
Army and Air Force 318,274 565,861
Navy 62,614 37,778
Marines 24,511 68,207
Coast Guard 1,917 Unknown
TOTAL 407,316 671,278
Mexican–American War
Sailors, Soldiers, and Marines of the Spanish-American War
https://www.archives.gov/publications/prologue/1998/spring/spanish-american-war
Statistics From the Civil War
https://www.facinghistory.org/resource-library/statistics-civil-war
Iraq
Almost 70 Percent Of U.S. Casualties In Iraq Under Age 30
https://www.mtv.com/news/d5706i/almost-70-percent-of-us-casualties-in-iraq-under-age-30