The Sherman Firefly was a tank used by the United Kingdom in World War II that traded mobility for fire power.
It was based on the ubiquitous US M4 Sherman tank, but fitted with the powerful 3-inch (76.2 mm) caliber British 17-pounder anti-tank gun as its main weapon to counter the heavy armor used by Germany's Wehrmacht in the European theater.
Originally conceived as a stopgap until future more powerful British tank designs came into service, the Sherman Firefly became the most common vehicle mounting the 17-pounder in the war.
This tag implicates tank (learn more).