A Company

The 405th is a UNSC Marine Corps unit.

Background
The 405th is based out of Diego Garcia. They arrived on scene during the First Battle of Earth in Mombasa, Kenya on Earth. They went on to fight on the city streets of New Mombasa valiantly.

The 405th assisted SPARTAN-117 in the destruction of a Scarab that was moving through the city. Surviving members of this unit then traveled to Installation 05 along with SPARTAN-117 aboard the. It is assumed all, or almost all of them, were killed in either the Battle of the Quarantine Zone or, although more unlikely, the First Battle of High Charity. It is also possible that they were attacked by the Flood as some of the Combat Forms spilled out on the In Amber Clad.

Roster
Known members of this unit include:
 * Unnamed Marine Officer
 * Staff Sergeant Banks
 * Corporal Perez
 * Private McKenzie
 * Private Parsons