The Colonial Militia is a branch of the UNSC Defense Force. Tasked with safeguarding human colonies when conventional UNSC Forces are not present, and possibly to act as support and scout units. A colony's militia forces are trained by the UNSC under the Colonial Militia Training Program.
Often trained and raised by non-commissioned officers in the UNSC, the Colonial Militia is comprised of citizens trained to provide defense, and emergency services and to serve as a potential paramilitary force. Often, militia members would later join the UNSC as enlisted soldiers, such as the case with Wallace Jenkins.
The Colonial Militia troops of the planet Harvest were among the first humans to make contact with the Covenant, following a secret operation in orbit above the planet. They were trained and commanded by Captain Ponder and Staff Sergeants Avery Johnson and Nolan Byrne. Despite their attempts to defend Harvest, the planet was ultimately glassed and nearly half of the Militia's seventy-two members were killed.
Another notable event involving the Colonial Militia would be during the Fall of Reach in 2552. Despite the fact that a militia was established on Reach, members of the UNSC looked down on the organization due to its smuggling of unauthorized weapons and explosives, as well as the Militia's unannounced establishment (unlike Harvest's). During the UNSC's first encounter with Reach's militia, the group's infantry were mistaken for Insurrectionists (which is still questionable due to their possession of stolen UNSC property). The only appearance of Reach's milita taking to arms was during Recon Team Bravo's reconnaissance mission in the mountains of Visegrád in August of 2552. Other than the militia's presence in Visegrád, there are no other known occurrences linked to Reach's militia, unless they were mistaken as the Insurrectionists elsewhere.
- Wallace Jenkins (later UNSC Marine Corps)
- Avery Johnson (temporary)
- Nolan Byrne (temporary)