Candidates' Challenge Marine Corps officer candidates participate in a fire team assault course at the Officer Candidate School at Marine Corps Base Quantico, Va., June 17, 2017. Candidates must go successfully complete three months of intensive training for commissioning as an officer. Marine Corps photo by Lance Cpl. Cristian L. Ricardo SHARE: Download: Full Size (2.98 MB) Credit: Lance Cpl. Cristian Ricardo VIRIN: 170617-M-BP749-084C.JPG Photo Gallery