From Wiki:
The Commander-in-Chief's Trophy is awarded to each season's winner of the American college football triangular series among the teams of the U.S. Military Academy (Army Black Knights), the U.S. Naval Academy (Navy Midshipmen), and U.S. Air Force Academy (Air Force Falcons).

The Navy–Air Force game is traditionally played on the first Saturday in October, the Army–Air Force game on the first Saturday in November, and the Army–Navy Game on the second Saturday in December. In the event of a tie, the award is shared, but the previous winner retains possession of the trophy. Along with the Florida Cup, the Michigan MAC Trophy, and the Beehive Boot, the Commander-in-Chief's Trophy is one of the few three-way rivalries that awards a trophy to the winner.

Through 2017, the Air Force Falcons hold the most trophy victories at 20 and the Navy Midshipmen have won 15. The Army Black Knights trail with only seven; their most recent came in 2017. The trophy has been shared on four occasions, most recently in 1993.