"Tiger killer"

The Sherman Firefly was a medium tank used by the United Kingdom and some armoured formations of other Allies in the Second World War. It was based on the US M4 Sherman but was fitted with the more powerful British 76.2 mm (3.00 in) calibre 17-pounder anti-tank gun as its primary weapon. Conceived as a stopgap until future British tank designs came into service, the Sherman Firefly became the most common vehicle mounting the 17-pounder in the war.

The British Army made extensive use of Sherman tanks, but they expected to have their own tank models developed soon, so the idea of mounting the 17-pounder in the Sherman was initially rejected. However, through the efforts of two persistent British officers, government reluctance was eventually overcome, and the Firefly went into production. This proved fortunate, as the Cruiser Mk VIII Challenger and Cruiser Mk VIII Cromwell tank designs experienced difficulties and delays.

After the problem of getting such a large gun to fit in the Sherman's turret was solved, the Firefly was put into production in early 1944, in time to equip the 21st Army Group, commanded by General Bernard Montgomery, for the Normandy landings. It soon became highly valued, as its gun could almost always penetrate the armour of the Panther and Tiger tanks it faced in Normandy, something no other British or American tank could reliably do.[2][3] Because the Firefly's barrel was visibly longer than that of a normal 75 mm Sherman, crews tried to countershade camouflage it so the tank would look like a regular Sherman from a distance. Between 2,100 and 2,200 were manufactured before production ended in 1945; it is unknown if this includes 100 tanks built for the United States.[3]