Italy agreed to an armistice with the Allies on September 3, 1943, with the stipulation that the Allies would provide military support to Italy in defending Rome from German occupation. Operation Giant II was a planned drop of one regiment of the 82nd Airborne Division northwest of Rome, to assist four Italian divisions in seizing the Italian capital. An airborne assault plan to seize crossings of the Volturno River during the Allied invasion of Italy, called Operation Giant, was abandoned in favor the Rome mission. However doubts about the willingness and capability of Italian forces to cooperate, and the distance of the mission far beyond support by the Allied military, resulted in the artillery commander of the 82nd, Brig. Gen. Maxwell Taylor (future commander of the 101st), being sent on a personal reconnaissance mission to Rome to assess the prospects of success. His report via radio on September 8 caused the operation to be postponed (and canceled the next day) as troop carriers loaded with two battalions of the 504th Parachute Infantry Regiment were warming up for takeoff.
With Giant II cancelled, Operation Giant I was laid on again for September 13 to drop two battalions of the 504th at Capua. However significant German counterattacks beginning September 12 resulted in a shrinking of the American perimeter and threatened destruction of the beachhead. As a result, Giant I was cancelled and the 504th instead dropped into the beachhead on the night of September 13 using transponding radar beacons as a guide. The next night the 505th PIR was also dropped into the beachhead as reinforcement. In all, 3,500 paratroopers made the most concentrated mass night drop in history, providing the model for the American airborne landings in Normandy in June 1944. An additional drop on the night of September 14–15 of the 2nd Battalion 509th PIR to destroy a key bridge at Avellino, to disrupt German motorized movements, was badly dispersed and failed to destroy the bridge before the Germans withdrew to the north.