▁of ▁the ▁rail ro ads ▁and ▁te legraph ▁for ▁military ▁use ▁in ▁January ▁ 1 8 6 2 . ▁ ▁In ▁practice , ▁however , ▁the ▁US MR R ▁restricted ▁its ▁authority ▁to ▁Southern ▁rail ▁lines ▁captured ▁in ▁the ▁course ▁of ▁the ▁war . ▁As ▁a ▁separate ▁organization ▁for ▁rail ▁transport ation ▁the ▁US MR R ▁is ▁one ▁of ▁the ▁prede cess ors ▁of ▁the ▁modern ▁United ▁States ▁Army ▁Transport ation ▁Corps . ▁ ▁History ▁ ▁The ▁American ▁Civil ▁War ▁was ▁the ▁first ▁war ▁where ▁rail ro ads ▁were ▁a ▁significant ▁factor ▁in ▁moving ▁troops ▁and ▁supp lying ▁forces ▁in ▁the ▁field . ▁The ▁United ▁States ▁Military ▁Rail road ▁organization ▁was ▁established ▁to ▁coordinate ▁this ▁new ▁cap ability ▁for ▁the ▁Union ▁Army . ▁The ▁US MR R ▁organization ▁benef ited ▁from ▁the ▁appointment ▁of ▁experienced ▁rail road ▁men ▁from ▁the ▁private ▁sector . ▁Thomas ▁A . ▁Scott , ▁vice - pres ident ▁of ▁the ▁Pennsylvania ▁Rail road ▁( PR R ), ▁served ▁as ▁an ▁Ass istant ▁Secretary ▁of ▁War ▁during ▁the ▁period ▁ 1 8 6 1 – 1 8 6 2 . ▁ ▁In ▁January ▁ 1 8 6 2 ▁Scott ▁prepared ▁a ▁report ▁on ▁military ▁transport ation ▁that ▁anticip ated ▁the ▁creation ▁of ▁the ▁US MR R . ▁Daniel ▁C . ▁Mc Call um , ▁former ▁general ▁super int endent ▁of ▁the ▁New ▁York ▁and ▁Er ie ▁Rail road , ▁was ▁appointed ▁as ▁Military ▁Director ▁and ▁Super int endent ▁of ▁U . S . ▁Rail ro ads . ▁H erman ▁Haupt