I Corps (Vietnamese: Quân đoàn I) was a corps of the Army of the Republic of Vietnam (ARVN), the army of the nation state of South Vietnam that existed from 1955 to 1975. It was one of four corps of the ARVN. This was the northernmost region of South Vietnam, bordering North Vietnam at the Vietnamese Demilitarized Zone (DMZ).
Bulgarian Lt. Col Petko Petkov, Paratrooper, 68th Bulgarian Special Forces Brigade chief of training, and other paratroopers with the 68th, conduct a brief with U.S. Air Force Capt. Mark Breed, 786th Security Forces Squadron operations officer, moments before participating in a static-line jump during Operation Thracian Spring, Bezmer Air Base, Bulgaria, March 9, 2009.