Production was limited by the availability of suitable tanks, with the phasing out of 75 mm Sherman production. To make up numbers, Sherman I and Sherman I Hybrids were also converted. From D-Day in June to the end of the Battle of Normandy in late August, almost 400 Sherman Fireflies were converted, more than sufficient to replace any permanent tank losses during the battle. In late 1944, with the creation of an effective high-explosive shell for the 17-pounder gun, British units started to receive two Fireflies per troop. By February 1945, some 2,000 Sherman Fireflies had been built and British, Commonwealth and Polish armoured units were equipped with a 50/50 mix of 75 mm and 17-pounder-armed Shermans.