Sergeant Major John L. Estrada, 15th Sergeant Major of the Marine Corps, talks to the Marines of 1st Marine Corps District and 2nd Battalion 25th Marine at Tun Tavern, the all-ranks club located at the 1st Marine Corps District Headquarters in Garden City, N.Y., July 14. - Sergeant Major John L. Estrada, 15th Sergeant Major of the Marine Corps, talks to the Marines of 1st Marine Corps District and 2nd Battalion 25th Marine at Tun Tavern, the all-ranks club located at the 1st Marine Corps District Headquarters in Garden City, N.Y., July 14.