Why Generals Are Called Flag Officers

Flag officer is naval in origin: officers of rear admiral rank and above flew their own distinguishing flag or pennant over the ships they commanded, so a fleet could see who led it. The Royal Navy formalized the colored, white, red, and blue squadrons in the seventeenth century, and admiral of the fleet crowned the system.

Armies borrowed the vocabulary in the twentieth century, and NATO now applies OF-6 and above as the flag officer band. The general officer titles are older still: general is short for captain general, the officer generalissimo of a state forces, and field marshal once literally commanded the marshalling of an army camp..