1 1 ▁January ▁ 1 8 0 0 . ▁ ▁The ▁second ▁ 1 3 th ▁Infantry ▁was ▁constit uted ▁ 1 1 ▁January ▁ 1 8 1 2 . ▁Following ▁the ▁War ▁of ▁ 1 8 1 2 ▁the ▁ 1 3 th ▁Infantry ▁was ▁cons olid ated ▁on ▁ 7 ▁May ▁ 1 8 1 5 , ▁with ▁the ▁ 4 th , ▁ 9 th , ▁ 2 1 st , ▁ 4 0 th , ▁and ▁ 4 6 th ▁Reg iments ▁into ▁a ▁new ▁ 5 th ▁Infantry ▁Regiment ▁whose ▁line age ▁continues ▁to ▁the ▁present . ▁ ▁A ▁new , ▁third ▁ 1 3 th ▁Infantry ▁Regiment ▁was ▁constit uted ▁in ▁May ▁ 1 8 6 1 ▁when ▁the ▁Army ▁expanded ▁the ▁Reg ular ▁Army ▁during ▁the ▁Civil ▁War . ▁General ▁William ▁T ec um seh ▁Sh erman ▁was ▁the ▁colon el ▁of ▁the ▁regiment ▁and ▁Philip ▁Sher idan ▁was ▁one ▁of ▁its ▁capt ains . ▁It ▁was ▁organized ▁as ▁one ▁of ▁the ▁nine ▁" three - b att alion " ▁reg iments ▁of ▁regular s , ▁each ▁batt alion ▁containing ▁eight ▁companies ▁of ▁inf antry , ▁in ▁contrast ▁to ▁the ▁original ▁ten ▁regular ▁reg iments ▁of ▁inf antry , ▁which ▁were ▁organized ▁on ▁the ▁traditional ▁ten - company ▁line . ▁ ▁During ▁the ▁American ▁Civil ▁War , ▁the ▁unit ▁earned ▁its ▁mot to ▁" First ▁at ▁V icks burg ". ▁It ▁participated ▁in ▁the ▁batt les ▁of ▁Hay es ▁Bl uff s , ▁Champion ▁Hill ,