Additionally; 
Dwight D. Eisenhower (48, born 1890), a lieutenant colonel in 1939.

George S. Patton (53, born 1885), a colonel.

Omar Bradley (46, born 1893), also a colonel, weren’t generals yet. Promotions accelerated after 1941, lowering the average age as the Army expanded.

Furthermore:

Thus, the average age of the signers of the Declaration of Independence on July 4, 1776, was approximately 44 years old.