Due to the sheer surplus of M4 Shermans available to the United States during World War II, a great number of separate tank battalions were formed; these were typically assigned to infantry divisions to grant frontline troops permanent armoured support, a luxury which their Comintern opponents never possessed.
The M4A3 Calliope is a modification of the regular late-war Sherman tank fit with a T34E2 Rocket Launcher with 60 tubes, each containing one M8 Rocket. These specialty vehicles were primarily employed to hammer through Sino-Soviet fortifications in the Eastern Front without needing to wait for artillery support. The T34 rocket launcher platform is jettisonable after being expended. Older M4A3 tanks with the original 75mm Gun M2 were usually modified, instead of the bleeding-edge 76mm variants.