The 5th Shock Troops Battalion, shortened as 5th Battalion and once referred to as the 5th Marine Expeditionary Unit, was a UNSC Marine Corps Shock Infantry, a subordinate unit to the 105th ODST Division and one of the seven constituents of the UNSC Naval Special Warfare. Commissioned in mid-2518, the 5th Battalion was one of many UNSC's active participants throughout the course of the Insurrection, and the Human-Covenant War.