A total of 500 A-36 dive bombers served in the Mediterranean and Southeast Asia theaters during World War II before being withdrawn from operational use in 1944.

The A-36 project was a stopgap measure intended to keep North American Aviation (NAA) assembly lines running during the first half of 1942 despite the US having exhausted its funds earmarked for fighter aircraft.

With the introduction of the North American Mustang Mk I with the Royal Air Force's Army Co-operation Squadrons in February 1942, the new fighter began combat missions as a low-altitude reconnaissance and ground-support aircraft.

The contract for 500 A-36A aircraft fitted with bomb racks, dive brakes, and heavier-duty wing, was signed by Kelsey on 16 April 1942,[5] even before the first flight of the first production P-51 in May 1942.

[6] With orders on the books, North American Aviation (NAA) began modifying the P-51 to accept the bomb shackles which had already been tested in a "long-range ferry" program that the RAF had stipulated.

Utilizing the basic P-51 airframe and Allison engine, structural reinforcing "beefed up" several high stress areas and "a set of hydraulically operated dive brakes were installed in each main wing plane".

[8] Due to the slightly inboard placement of the bomb racks and unique installation of four cast aluminum dive brakes, a complete redesign of the P-51 wing was required.

Charles E. Dills, 522d Fighter Squadron, 27th FBG, XIIth Air Force emphatically stated in a postwar interview: "I flew the A-36 for 39 of my 94 missions, from 11⁄43 to 3⁄44.

[19] This order was generally ignored by experienced pilots, but some units did wire dive brakes shut until modifications made to the hydraulic actuators.

[14] Both groups were actively involved in air support during the Sicilian campaign, becoming especially adept at "mopping up" enemy gun positions and other strong points as the Allies advanced.

[13] As fighting intensified in all theaters where the A-36A operated, the dive bomber began to suffer an alarming loss rate with 177 falling to enemy action.

[22] Despite establishing a reputation for reliability and performance, the one "Achilles' heel" of the A-36A (and the entire Mustang series) remained the ventral-fuselage location of the radiator/cooling system, leading to many of the losses.

However, the A-36A fought at a significant disadvantage, having to carry out long-range missions often at altitudes above The Hump that meant its Allison engine was below peak performance.

"The type's relatively brief service life should not camouflage the fact that it made a major contribution to the Allied war effort"[13] especially in the Mediterranean and it amounted to the first USAAF combat use of a Mustang variant.

In a well-planned attack on the large, well defended rail depot and ammunition dump at Orte, Italy, Lieutenant Ross C. Watson led a flight of four A-36s through a heavy overcast on the approach to the target.

Under continuing heavy ground fire, Watson pressed home his attack and destroyed the ammunition dump before making an emergency landing at an advanced Allied airfield.