Battle of Axanar

From Memory Alpha, the free Star Trek reference.

The Battle of Axanar was a battle fought by the Federation at Axanar, led by Fleet Captain Garth of Izar.

Garth's tactics and actions in this battle were required reading at Starfleet Academy. (TOS: "Whom Gods Destroy")

It was not revealed whether the Federation was involved in a battle against Axanar, or if they were allied with Axanar against another party. Its also possible Axanar was under siege or even neutral in the conflict.