In the spring of 1945, Ninth Air Force troop carrier units flew airborne parachute and glider units again during Operation Varsity, the Allied assault over the Rhine River on 24 March 1945. Operation Varsity was the single largest airborne drop in history. The operation saw the first use of the Curtiss-Wright C-46 Commando transport in Europe, operating with the reliable C-47 Skytrain of previous airborne operations, an experiment which ended with the catastrophic loss of 28% of the C-46s participating.