From late 1943, P-51Bs and Cs (supplemented by P-51Ds from mid-1944) were used by the USAAF's Eighth Air Force to escort bombers in raids over Germany, while the RAF's Second Tactical Air Force and the USAAF's Ninth Air Force used the Merlin-powered Mustangs as fighter-bombers, roles in which the Mustang helped ensure Allied air superiorityin 1944.^[10] The P-51 was also used by Allied air forces in the North African, Mediterranean, Italian and Pacific theaters. During World War II, Mustang pilots claimed to have destroyed 4,950 enemy aircraft.^{[nb 2]}

At the start of the Korean War, the Mustang, by then redesignated F-51, was the main fighter of the United Nations until jet fighters, including North American's F-86, took over this role; the Mustang then became a specialized fighter-bomber. Despite the advent of jet fighters, the Mustang remained in service with some air forces until the early 1980s. After the Korean War, Mustangs became popular civilian warbird and air racing aircraft.

During the Battle of Britain, from July to October 1940, the public perceived the Spitfire to be the main RAF fighter, though the more numerous Hawker Hurricane shouldered a greater proportion of the burden against Nazi Germany's air force, the Luftwaffe. However, Spitfire units had a lower attrition rate and a higher victory-to-loss ratio than those flying Hurricanes because of the fighter's higher performance. During the Battle, Spitfires were generally tasked with engaging Luftwaffe fighters—mainly Messerschmitt Bf 109E series aircraft—which were a close match for them.

After the Battle of Britain, the Spitfire superseded the Hurricane to become the backbone of RAF Fighter Command, and saw action in the European, Mediterranean, Pacific, and South-East Asian theatres. Much loved by its pilots, the Spitfire served in several roles, including interceptor, photo-reconnaissance, fighter-bomber and trainer, and it continued to serve in these roles until the 1950s. The Seafire was a carrier-based adaptation of the Spitfire which served in the Fleet Air Arm from 1942 through to the mid-1950s. Although the original airframe was designed to be powered by a Rolls-Royce Merlin engine producing 1,030 hp (768 kW), it was strong enough and adaptable enough to use increasingly powerful Merlins and, in later marks, Rolls-Royce Griffon engines producing up to 2,340 hp (1,745 kW). As a result, the Spitfire's performance and capabilities improved over the course of its service life.

The P-47 was one of the main United States Army Air Forces (USAAF) fighters of World War II, and also served with other Allied air forces, including those of France, the United Kingdom, and the Soviet Union. Mexican and Brazilian squadrons fighting alongside the USAAF also flew the P-47.

The armored cockpit was relatively roomy and comfortable and the bubble canopy introduced on the P-47D offered good visibility. Nicknamed the "Jug" owing to its appearance if stood on its nose, the P-47 was noted for its firepower, as well as its ability to resist battle damage and remain airworthy. A present-day U.S. ground-attack aircraft, the Fairchild Republic A-10 Thunderbolt II, takes its name from the P-47.

Unlike the F Mk II, the ventral bay doors were split into two pairs, with the forward pair being used to access the cannon, while the rear pair acted as bomb bay doors. The maximum fuel load was 719.5 imp gal (3,271 l) distributed between 453 imp gal (2,060 l) internal fuel tanks, plus two overload tanks, each of 66.5 imp gal (302 l) capacity, which could be fitted in the bomb bay, and two 100 imp gal (450 l) drop tanks. All-out level speed is often given as 368 mph (592 km/h), although this speed applies to aircraft fitted with saxophone exhausts. The test aircraft (HJ679) fitted with stub exhausts was found to be performing below expectations. It was returned to de Havilland at Hatfield where it was serviced. Its top speed was then tested and found to be 384 mph (618 km/h), in line with expectations. 2,298 FB Mk VIs were built, nearly one-third of Mosquito production. Two were converted to TR.33 carrier-borne, maritime strike prototypes.

The FB Mk VI proved capable of holding its own against fighter aircraft, in addition to strike/bombing roles. For example, on 15 January 1945 Mosquito FB Mk VIs of 143 Squadron were engaged by 30 Focke-Wulf Fw 190s from Jagdgeschwader 5: the Mosquitos sank an armed trawler and two merchant ships, but five Mosquitos were lost (two reportedly to flak), while shooting down five Fw 190s.