▁Ra id ▁of ▁April ▁ 2 , ▁ 1 9 0 9 . ▁Just ▁south west ▁of ▁Ten ▁S leep , ▁Wy oming , ▁the ▁she e pher der ▁Joe ▁Al lem and ▁and ▁two ▁of ▁his ▁compan ions ▁were ▁shot ▁and ▁killed ▁by ▁seven ▁or ▁eight ▁mask ed ▁men . ▁The ▁ra iders ▁also ▁killed ▁about ▁twenty - five ▁sheep ▁and ▁two ▁dogs , ▁and ▁burn ed ▁the ▁w ag ons ▁with ▁k eros ene . ▁Because ▁sheep ▁ra iders ▁had ▁never ▁been ▁pro sec uted ▁in ▁a ▁Wy oming ▁court ▁before , ▁many ▁believed ▁that ▁the ▁murder ers ▁would ▁get ▁away ▁with ▁the ▁mass acre . ▁However , ▁seven ▁men ▁were ▁eventually ▁arrested , ▁five ▁of ▁whom ▁were ▁sent ▁to ▁prison . ▁The ▁conv iction ▁of ▁the ▁Ten ▁S leep ▁murder ers ▁brought ▁peace ▁to ▁Big ▁Horn ▁County . ▁After ▁the ▁ 1 9 0 9 ▁attack , ▁cattle men ▁were ▁rel uct ant ▁to ▁ra id ▁sheep ▁cam ps ▁because ▁now ▁they ▁risk ed ▁being ▁pun ished ▁for ▁it . ▁Though ▁there ▁were ▁two ▁more ▁Wy oming ▁sheep ▁ra ids ▁in ▁ 1 9 1 1 ▁and ▁ 1 9 1 2 , ▁no ▁more ▁she e ph erd ers ▁were ▁murder ed . ▁The ▁last ▁known ▁sheep ▁ra id ▁in ▁Colorado ▁occurred ▁eight ▁years ▁later , ▁in ▁ 1 9 2 0 , ▁when ▁ 1 5 0 ▁sheep ▁were ▁sla ugh tered ▁for ▁gra zing ▁in ▁the ▁White ▁River ▁National ▁Forest . ▁ ▁According ▁to ▁Robert ▁El man