 The T30 HMC was originally conceived in 1941 as an interim design to fulfil the Armored Force 's requirement for an assault gun to equip tank and armored reconnaissance units . The Ordnance Department design was based on the M3 Half @-@ track in order that it could be brought into service quickly . A prototype vehicle was authorized in October 1941 armed with an M1A1 75 mm Pack Howitzer and a mount that was designed to fit on a simple box structure in the back of an M3 Half @-@ track . 
 The T30 HMC was originally conceived in 1941 as an interim design to fulfil the Armored Force <a href='null_genetive' title='1'><mark>'s</mark></a>requirement for an assault gun to equip tank and armored reconnaissance units . The Ordnance Department design was based on the M3 Half @-@ track in order that it could be brought into service quickly . A prototype vehicle was authorized in October 1941 armed with an M1A1 75 mm Pack Howitzer and a mount <a href='null_relcl' title='2'><mark>that</mark></a>was designed to fit on a simple box structure in the back of an M3 Half @-@ track . 
Da T30 HMC was originally conceived in 1941 as an interim design to fulfil the Armored Force  requirement for an assault gun to equip tank and armored reconnaissance units . The Ordnance Department design was based on tdaM3 Half @-@ track in order that it could be brought into service quickly . A prototype vehicle was authorized in October 1941 armed witt an M1A1 75 mm Pack Howitzer and a mount was designed to fit on a simple box structure in thdaack of an M3 Half @-@ track .