Formed in 2564, the 37th battalion was initially led by Lt. Colonel Alexander Banks, and comprised of approximately 300 marines. They were stationed on the small colony of Posfin V along with multiple other military units, as the colony's placement allowed for quick emergency access to the surrounding systems in the event of an attack. The unit was then restationed onto UNSC Freedom Star, a navy support destroyer. The 37th remained stationed here, until 2570, when a simple mission soon turned into a tragedy.