Brig. Gen. Terry V. Williams, commanding general of Marine Corps Recruit Depot Parris Island and Eastern Recruiting Region, speaks during the 75th anniversary of Officer Candidate School on Brown Field ceremony and candidate graduation at Marine Corps Base Quantico, Virginia. Nov. 24, 2015. The mission of OCS is to educate and train officer candidates in Marine Corps knowledge and skills within a controlled, challenging and chaotic environment. (U. S. Marine Corps photo by Lance Cpl. Erasmo Cortez III) - Brig. Gen. Terry V. Williams, commanding general of Marine Corps Recruit Depot Parris Island and Eastern Recruiting Region, speaks during the 75th anniversary of Officer Candidate School on Brown Field ceremony and candidate graduation at Marine Corps Base Quantico, Virginia. Nov. 24, 2015. The mission of OCS is to educate and train officer candidates in Marine Corps knowledge and skills within a controlled, challenging and chaotic environment. (U. S. Marine Corps photo by Lance Cpl. Erasmo Cortez III)