Ruhrstahl-Kramer X4 air-to-air guided missile

Considered to be the first air-to-air missile to be used successfully in World War 2, the X4 was a short range, wire-guided, rocket-pow­ered AAM that was extensively tested after being conceived at the start of 1943. The X4 was test launched from a number of aircraft such as the Junkers Ju 188L and Focke-Wulf Fwl90F-8 and was envisioned that the Messerschmitt Me 262 would carry the X4 into operational service. Despite 1,300 being built – and suggestions that some were test fired in action against American bombers – no X4 saw active service. Allied intelligence ser­vices assumed that the Japanese were aware of the X4 development but no evidence has surfaced to confirm this.