The U.S. Army in 1940 was in the early stages of developing an airborne capability to exploit the vertical envelopment concept. That concept became reality in 1942 with the first airborne operation in North Africa. Although the first parachute drop contributed virtually nothing to the overall success of the mission, it was the beginning of an important capability.
In 1943, the War Department authorized five airborne divisions despite a lack of experience and doctrine to direct the new organizational structure. The airborne initiative expanded much more quickly than did the doctrine, training, or employment principles. The first attempts of conducting large-scale airborne operations in combat during the Sicilian Campaign that year proved to be disastrous. Because of these
failures, the airborne division, as well as the vertical envelopment concept itself, were in jeopardy. Army Chief of Staff George C. Marshall appointed a special board to investigate the causes of the disasters and make recommendations as to the soundness of the airborne division.
While the board was meeting, half-way around the world in the South West Pacific Area, a successful airborne operation occurred when the 503d Parachute Infantry Regiment executed a drop at the Nadzab Emergency Landing Strip that allowed the capture of the essential port of Lae, New Guinea. This operation had a broader impact than just the tactical objectives that it achieved. This was the first unqualified successful American airborne operation of World War II and it allowed the airborne advocates to make a case for the soundness of the vertical envelopment concept, as well as that of the airborne division. Had it not been for this parachute drop, the U.S. Army might have abandoned the whole initiative just when it was planning to employ two airborne divisions during Operation NEPTUNE, the airborne portion of Operation OVERLORD.