, ▁and ▁ 3 2   mm ▁front al ▁arm or . ▁The ▁Pan zer ▁III ▁and ▁Pan zer ▁IV ' s ▁success ▁in ▁the ▁French ▁campaign ▁led ▁the ▁U . S . ▁Army ▁to ▁immediately ▁order ▁a ▁new ▁medium ▁tank ▁armed ▁with ▁a ▁ 7 5   mm ▁gun ▁in ▁a ▁tur ret ▁as ▁a ▁response . ▁This ▁would ▁be ▁the ▁M 4 ▁Sh erman . ▁Until ▁the ▁Sh erman ▁reached ▁production , ▁an ▁inter im ▁design ▁with ▁a ▁ 7 5   mm ▁gun ▁was ▁ur g ently ▁needed . ▁ ▁The ▁M 3 ▁was ▁the ▁solution . ▁The ▁design ▁was ▁unusual ▁because ▁the ▁main ▁weapon ▁– ▁a ▁larger ▁cal iber , ▁medium - vel ocity ▁ 7 5   mm ▁gun ▁– ▁was ▁in ▁an ▁offset ▁spons on ▁mounted ▁in ▁the ▁h ull ▁with ▁limited ▁traverse . ▁The ▁spons on ▁mount ▁was ▁necessary ▁because , ▁at ▁the ▁time , ▁American ▁tank ▁plants ▁did ▁not ▁have ▁the ▁design ▁experience ▁necessary ▁to ▁make ▁a ▁gun ▁tur ret ▁capable ▁of ▁holding ▁a ▁ 7 5   mm ▁weapon . ▁A ▁small ▁tur ret ▁with ▁a ▁l ighter , ▁high - vel ocity ▁ 3 7   mm ▁gun ▁sat ▁on ▁top ▁of ▁the ▁tall ▁h ull . ▁A ▁small ▁cup ola ▁on ▁top ▁of ▁the ▁tur ret ▁held ▁a ▁machine ▁gun . ▁The ▁use ▁of ▁two ▁main ▁guns ▁was ▁seen ▁on ▁the ▁French ▁Char ▁B 1 ▁and ▁the ▁Mark ▁I ▁version ▁of ▁the ▁British ▁Church ill ▁tank . ▁In ▁each ▁case , ▁two