In 2017 total U.S. military personnel numbered 2,363,675 with 1,373,650 active and 990,025 in reserve. (DoD photo by Petty Officer 1st Class Daniel N. Woods, U.S. Navy). 
Ike on D-Day (Wikimedia Commons)
US MILITARY PERSONNEL (1939-1945)
| Year | Army | Navy | Marines | Coast Guard | Total |
|---|---|---|---|---|---|
| 1939 | 189,839 | 125,202 | 19,432 | 334,473 | |
| 1940 | 269,023 | 160,997 | 28,345 | 458,365 | |
| 1941 | 1,462,315 | 284,427 | 54,359 | 1,801,101 | |
| 1942 | 3,075,608 | 640,570 | 142,613 | 56,716* | 3,915,507 |
| 1943 | 6,994,472 | 1,741,750 | 308,523 | 151,167 | 9,195,912 |
| 1944 | 7,994,750 | 2,981,365 | 475,604 | 171,749 | 11,623,468 |
| 1945 | 8,267,958 | 3,380,817 | 474,680 | 85,783 | 12,209,238 |
*Coast Guard listed only as wartime strength