▁Service ▁Corps ▁also ▁used ▁them ▁to ▁ha ul ▁long ▁trains ▁of ▁fre ight ▁w ag ons ▁over ▁the ▁un im pro ved ▁d irt ▁tracks ▁behind ▁the ▁front . ▁They ▁were ▁particularly ▁useful ▁in ▁October ▁ 1 9 1 7 , ▁when ▁Britain ▁and ▁France ▁each ▁sent ▁six ▁divisions ▁to ▁assist ▁the ▁It ali ans . ▁Hol t ▁tra ctors ▁fer ried ▁the ▁supplies ▁and ▁am mun ition ▁over ▁the ▁ste ep ▁and ▁tw isting ▁mountain ▁roads ▁in ▁less ▁than ▁two ▁weeks . ▁Two ▁companies ▁of ▁Hol t ▁tra ctors ▁with ▁the ▁dual ▁role ▁of ▁gun - t ract ors ▁and ▁supply ▁trains ▁were ▁also ▁used ▁in ▁the ▁Mes op ot am ia ▁campaign ▁ ▁In flu ence ▁on ▁development ▁of ▁t anks ▁▁ ▁In ▁Europe , ▁Major ▁Ernest ▁Sw inton , ▁sent ▁to ▁France ▁as ▁an ▁army ▁war ▁correspond ent , ▁very ▁soon ▁saw ▁the ▁potential ▁of ▁a ▁track - lay ing ▁tra ctor . ▁ ▁He ▁proposed ▁to ▁Sir ▁Maurice ▁Han key , ▁Secretary ▁of ▁the ▁Committee ▁of ▁Imperial ▁Def ence , ▁that ▁the ▁British ▁build ▁a ▁power - dri ven , ▁bullet - proof , ▁track ed ▁vehicle ▁that ▁could ▁destroy ▁enemy ▁machine - g uns . ▁Hol t ▁tra ctors ▁were ▁" the ▁insp iration ▁for ▁the ▁development ▁of ▁the ▁British ▁tank ." ▁▁ ▁The ▁British ▁War ▁Office ▁carried ▁out ▁a ▁rud iment ary ▁trial ▁with ▁a ▁Hol t ▁tra ctor . ▁ ▁Several ▁key ▁figures ▁in ▁tank ▁development , ▁including ▁J . B . E . ▁Est ienne