The 1st Terra Auxilia is a military unit the size of a UNSC Division. To foster relationships between the Terran and Sangheili soldiers, the Sangheili-Terran Alliance allowed for both sides to exchange soldiers to serve in each other's military. The 1st Terra Auxilia was a mixed Terran-Sangheili unit allowing for inter-species operations, however the Terrans used Sangheili weaponry. The Sangheili equivalent is the Sangii Legion, Sangii meaning Blood Allied in Sangheili tongue.