le ▁their ▁bar ric ades . ▁Else where , ▁they ▁hit ▁civ ili ans ▁with ▁their ▁rif le ▁but ts ▁to ▁drive ▁them ▁off . ▁ ▁The ▁British ▁military ▁were ▁caught ▁totally ▁un prep ared ▁by ▁the ▁re bell ion ▁and ▁their ▁response ▁of ▁the ▁first ▁day ▁was ▁generally ▁un - co ordin ated . ▁Two ▁troops ▁of ▁British ▁caval ry ▁were ▁sent ▁to ▁investigate ▁what ▁was ▁happening . ▁They ▁took ▁fire ▁and ▁cas ual ties ▁from ▁re bel ▁forces ▁at ▁the ▁G PO ▁and ▁at ▁the ▁Four ▁Cour ts . C off ey , ▁Thomas ▁M . ▁Ag ony ▁at ▁E aster : ▁The ▁ 1 9 1 6 ▁Irish ▁U pr ising , ▁pp . ▁ 3 8 , ▁ 4 4 , ▁ 1 5 5 ▁As ▁one ▁tro op ▁passed ▁Nelson ' s ▁P ill ar , ▁the ▁reb els ▁opened ▁fire ▁from ▁the ▁G PO , ▁killing ▁three ▁caval ry men ▁and ▁two ▁horses ▁and ▁fat ally ▁w ounding ▁a ▁fourth ▁man . ▁The ▁caval ry men ▁retre ated ▁and ▁were ▁with dra wn ▁to ▁bar ra cks . ▁On ▁Mount ▁Street , ▁a ▁group ▁of ▁Vol unte er ▁Training ▁Corps ▁men ▁st umbled ▁upon ▁the ▁re bel ▁position ▁and ▁four ▁were ▁killed ▁before ▁they ▁reached ▁Beg g ars ▁Bush ▁Bar ra cks . ▁ ▁The ▁only ▁substantial ▁combat ▁of ▁the ▁first ▁day ▁of ▁the ▁R ising ▁took ▁place ▁at ▁the ▁South ▁Dublin ▁Union ▁where ▁a ▁pi quet ▁from ▁the ▁Royal ▁Irish ▁Regiment ▁encountered ▁an ▁out post ▁of