Actium

Actium was a human colony world likely situated within the Inner Colonies of the Unified Earth Government's interstellar empire.

The colony was discovered by the Covenant Empire in May 2545 and the proceeding Battle of Actium took place for less than a month, ending in the total destruction of nearby UNSC defenses and the worlds inevitable glassing. Before that happened, however, the planet's defenders managed to inflict heavy casualties on the Covenant.

Trivia
The colony is likely named after Actium, a promontory in western Greece which was the site of a major battle during the Final War of the Roman Republic.