The Spitfire Mk XVI was developed in 1944 from the earlier MK IX model, when it was made evident during operation that, during that period of the war, most cross fires were battled at lower altitudes with respect to the past. The engineers answer to this was the implementation of Packard Merlin 266 1.372hp engines, manufactured under licence to Rolls Royce in the United States, and better adapted for low altitudes. Another important modification, introduced during production stage, was the bubble canopy, which offered improved visibility in all flight phases. Introduced into operation at the beginning of 1945, the Mk.XVI was flown right up to the end of the Second World War, principally for ground attacks: following the end of the war many aircraft remained in function for several years; total production of this model, including the LF.XVI with the wingtip bolts, was 1054.