Candidates with the U.S. Marine Corps Officer Candidates School (OCS) post security as they crawl through 'The Quigley' during the combat course at OCS, Marine Corps Base Quantico, Virginia, June 18, 2018.
Candidates must go through three months of intensive training to evaluate and screen individuals for the leadership, moral, mental, and physical qualities required for commissioning as a U.S. Marine Corps officer. (U.S. Marine Corps photo by Sgt. Jacqueline A. Clifford) www.dvidshub.net. Original public domain image from Flickr