American fighter pilots in the skies over the Reich quickly realized the best counter to the Messerschmitt Me 262 jet was to catch it at its airfields during takeoff and landing where long engine spool up times and low altitudes negated its speed advantage. To protect the -262 bases, not only did they boast robust AAA defenses, but German ace Adolf Galland formed a special airfield protection unit called the Platzschutzstaffel that flew Focke Wulf Fw 190D-9s- the Dora 9s had outstanding low to medium altitude performance to catch the marauding American fighters.

In response, North American developed a rocket-boosted Mustang to take in the Me 262s at altitude rather than run the gauntlet of airfield defenses. An Aerojet liquid fuel rocket engine powered by red fumaric acid and aniline was installed in the rear fuselage ahead of the tail wheel and behind the radiator exhaust. 75 gallons of fuel for the rocket were carried in pressurized underwing tanks, enough for 1 minute of operation that gave the P-51 a 100 mph boost. On 23 April 1945 the rocket Mustang was successfully flight tested, but the surrender of the Reich on 8 May ended the project.