Beach Rehearsal Marines assault the beach at Lake Margrethe at Camp Grayling, Mich., Aug. 13, 2016, to rehearse amphibious assault operations during Northern Strike 16. The National Guard Bureau-sponsored exercise unites about 5,000 Army, Air Force, Marine and Special Forces service members from 20 states and three coalition countries to provide opportunities to build readiness for military units. Air National Guard photo by Master Sgt. Scott Thompson SHARE: Download: Full Size (2.06 MB) Credit: Master Sgt. Scott Thompson VIRIN: 160813-Z-GS745-1312C.JPG Photo Gallery