As seen through a night-vision device, a U.S. Air Force C-130J Super Hercules aircraft takes off from Bagram Airfield, Afghanistan, Aug. 7, 2015, after receiving maintenance. The maintainers are assigned to the 455th Expeditionary Aircraft Maintenance Squadron. U.S. Air Force photo by Tech. Sgt. Joseph Swafford

The U.S. Air Force deployed six F-16 Fighting Falcons from Aviano Air Base, Italy -- plus support equipment and approximately 300 personnel -- to Incirlik Air Base, Turkey, Aug. 9, 2015, in support of Operation Inherent Resolve. The deployment follows Turkey’s decision to host the U.S. aircraft conducting counter-ISIL operations to promote peace and stability in the region. U.S. Air Force photo by Senior Airman Krystal Ardrey

Smoke from the Stouts fire plumes over the forests outside Milo, Ore., Aug. 5, 2015. Two Oregon Army National Guard HH-60M Black Hawk helicopters were working out of the Roseburg Municipal Airport to support ground firefighting crews battling the Stouts fire near Canyonville, Ore., which had burned approximately 15,000 acres. Oregon Army National Guard photo by Staff Sgt. Jason van Mourik

U.S. airmen participate in a tactical combat casualty care scenario during a three-day combat readiness training exercise on Kunsan Air Base, South Korea, Aug. 3, 2015. The airmen are assigned to the 8th Security Forces Squadron. Training included mounted and dismounted operations, individual and small unit tactics, land navigation, enemy prisoner of war procedures and self-aid buddy care. U.S. Air Force photo by Staff Sgt. Nick Wilson

Marines apply camouflage paint before a helicopter raid on Marine Corps Base Camp Pendleton, Calif., Aug. 4, 2015. The Marines are assigned to 1st Marine Division’s 3rd Battalion, 5th Marine Regiment. U.S. Marine Corps photo by Cpl. Demetrius Morgan

U.S. Army Sgt. David Pileggi paddles across a lake while tackling an obstacle course at the Nowa Deba Training Area in Poland, Aug. 6, 2015. The water course was created by Polish soldiers from the 6th Airborne Brigade. The training is part of Operation Atlantic Resolve, an ongoing multinational partnership focused on combined training and security cooperation between NATO allies. U.S. Army photo by Spc. Marcus Floyd

Deputy Defense Secretary Bob Work, center, talks with Army Special Forces members as they display some of their equipment at Fort Irwin, Calif., Aug. 5, 2015. Work also observed a large-scale training exercise as part of his visit. DoD photo by U.S. Air Force Master Sgt. Adrian Cadiz

On Aug. 7, 1782, General George Washington created the "Badge for Military Merit," which evolved to become the Purple Heart. Today, on National Purple Heart Day, the Defense Department honors those killed or wounded in combat and celebrates their service.