In the early months of 1942, the Spitfire Mk VB was clearly outclassed by the superiority of the Focke-Wulf Fw 190. With the introduction of the Spitfire Mk IX, powered by the two-stage supercharged Merlin 61 engine, its performance was a quantum leap over that of the Mk VB especially at heights above 20,000 feet. It became a truly deadly counter to Germany's Messerschmitt Bf 109 and Focke-Wulf Fw 190.