▁tracks , ▁the ▁Horn s by ▁craw ler ▁was ▁ste ered ▁by ▁cont rolling ▁power ▁to ▁each ▁track . ▁Hol t ▁was ▁more ▁interested ▁in ▁the ▁Horn s by ' s ▁differential ▁than ▁in ▁its ▁complex ▁track ▁system . ▁ ▁When ▁World ▁War ▁I ▁broke ▁out , ▁with ▁the ▁problem ▁of ▁tren ch ▁war fare ▁and ▁the ▁difficulty ▁of ▁transport ing ▁supplies ▁to ▁the ▁front , ▁the ▁pulling ▁power ▁of ▁craw ling - type ▁tra ctors ▁drew ▁the ▁attention ▁of ▁the ▁military . ▁Company ▁Vice - Pres ident ▁and ▁general ▁manager ▁Pl iny ▁Hol t ▁had ▁retired ▁and ▁tra ve led ▁to ▁Washington ▁D . C . ▁to ▁offer ▁his ▁services , ▁and ▁was ▁appointed ▁by ▁, ▁Chief ▁of ▁Or dn ance , ▁to ▁serve ▁as ▁chairman ▁of ▁the ▁board ▁organized ▁to ▁handle ▁the ▁production ▁of ▁the ▁" C ater p ill ar " ▁Art illery ▁program . ▁ ▁The ▁British ▁War ▁Office ▁ordered ▁a ▁Hol t ▁tra ctor ▁and ▁put ▁it ▁through ▁tri als ▁at ▁Ald ers hot . ▁Although ▁it ▁was ▁not ▁as ▁powerful ▁as ▁the ▁ ▁F oster - Da im ler ▁tra ctor , ▁the ▁ ▁Hol t ▁was ▁better ▁su ited ▁to ▁ha ul ▁heavy ▁loads ▁over ▁une ven ▁ground . ▁Without ▁a ▁load , ▁the ▁Hol t ▁tra ctor ▁managed ▁a ▁walking ▁pace ▁of ▁. ▁Tow ing ▁a ▁load , ▁it ▁could ▁manage ▁. ▁Most ▁important ly , ▁Hol t ▁tra ctors ▁were ▁readily ▁available ▁in ▁quantity . ▁The ▁War ▁Office ▁was ▁suit ably ▁im pressed ▁and