The P-51 Mustang was the excellent long range fighter aircraft which since late 1943 was the first to provide US heavy bombers with the type of escort they needed in order to efficiently destroy Nazi Germany's war production. Unlike earlier shorter-range allied fighters used for bomber escort, like the Spitfire, the P-47 and the P-38, the new P-51 Mustang was the first fighter which:
With these two significant advantages, the P-51 Mustang dramatically reduced the losses of the heavy bombers, shot down an increasing number of German fighters, and eventually also attacked many ground targets, mostly small but important ground targets which were too small for the high flying heavy bomber formations.
It was a cycle which gradually and systematically eroded the Luftwaffe and achieved allied air superiority deep over Nazi Germany.
Many of the bombarded targets were directly related to the Luftwaffe's ability to keep fighting, for example aircraft factories, and the fuel industry, which was systematically decimated. So after each such massive bombardment the German industry could produce less new fighters to replace combat losses, and of the fewer fighters, even fewer were actually able to take off and intercept the heavy bombers and face their Mustang escorts, because they suffered an increasingly severe shortage of fuel, spare parts, etc.
As a result of that, fewer heavy bombers were shot down by the German fighters and so more and more bombers participated in those bombardments, further increasing their damage to the German industry and so on.
The ever smaller number of German fighters available for interception missions meant that the German fighters were increasingly outnumbered over their own territory. Instead of facing swarms of hundreds of Me-109s and Fw-190s, the heavy bombers and their Mustang escorts gradually met smaller numbers of German fighters and were able to shoot down more of them, literally decimating the Luftwaffe, and further reducing losses among the heavy bombers.
Once local air superiority around the bomber formations was achieved, the P-51 Mustang pilots were able to go to the next step, storming Luftwaffe airfields and other ground targets and ambushing the German fighters at takeoff and landing.
This tactic was especially efficient against the Luftwaffe's new "wonder weapons", the new jet and rocket fighters. At high altitude and at full speed, the Mustang could not chase the much faster Me-262 jet fighters, so instead the Mustang pilots followed the German jets to their airfields where they shot them down as they descended at low speed for landing.
Over all, it was a classic example of a strategic campaign to achieve air superiority by destroying the enemy Air Force's ground infrastructures and by massively engaging it in the air while doing so.
The presence of the Mustangs over the heart of Germany also pulled a significant part of the Luftwaffe's tactical fighter squadrons from the war fronts to the center of Germany, which meant that tactical aircraft of The Allies could smash German ground units, especially German armor, with much greater ease.
The other great benefit of the air campaign over Germany, which was its goal in the first place, was that the huge formations of heavy bombers, efficiently protected by the P-51 Mustang "Little friends", were able to efficiently bring the mighty German war machine to a standstill. German war production of all types was significantly damaged and just like the grounded German jets, the German tanks in the battlefield also suffered extreme shortage of fuel and spare parts. For example, many of Germany's new mighty King Tiger tanks were simply abandoned in the field for lack of fuel.
One of the most successful fighter projects ever, the P-51 Mustang was North American's first fighter project. It was initially ordered in 1940 by the Royal Air Force which used it as a ground attack aircraft thanks to its high speed at low altitude and its long range. In 1942 the British made an experiment. They installed their superb 1500hp Rolls-Royce Merlin fighter engine in four Mustangs and tested them. The result was spectacular, clearly an excellent fighter, with an unprecedented range of 2080 miles (3347km) with external fuel tanks. This was the aircraft which later dominated the sky over Germany.
It was produced in very large numbers in several successively improved types. A total of 15,586 Mustangs were produced, and almost 8000 of them were of the most popular D type, which had a tear-drop shaped cockpit canopy. It had a high altitude speed of 704 km/h (437mph). It was armed with six 0.5" machine guns. Not a heavy armament compared with other fighters, but definitely enough against enemy fighters, its main target, and for strafing unarmored ground targets. For ground attack missions it could also carry two 1000lb bombs instead of the external fuel tanks, or six 5" rockets.
After World War 2 the Mustang served in no less than 55 air forces worldwide, and although it was the supersonic jet age by then, small numbers were even produced in 1967 for various military purposes, another proof of how excellent this aircraft was.
The most famous Mustang pilot and ace is Chuck Yeager. Yeager was the ultimate fighter pilot. As a young Mustang pilot he once downed five German fighters in one mission. He downed two much faster Me-262 jet fighters, escaped captivity after being shot down over occupied France, and when the war ended, it was still just the beginning of his amazing career. After the war Yeager became a test pilot, and in 1947 he earned his place in the history books as the first man who "broke the sound barrier" in the daring first supersonic flight.