. ▁Uruguay ▁was ▁inv aded ▁and ▁an nex ed ▁by ▁Brazil ▁in ▁ 1 8 1 6 , ▁until ▁the ▁Th irty - Three ▁Orient als ▁led ▁an ▁ins urre ction ▁to ▁re join ▁the ▁United ▁Provin ces . ▁This ▁began ▁the ▁C is pl at ine ▁War , ▁which ▁ended ▁with ▁the ▁Tre aty ▁of ▁Monte video ▁that ▁made ▁Uruguay ▁a ▁new ▁state . ▁ ▁When ▁Argent ine ▁forces ▁returned ▁to ▁Buenos ▁Aires , ▁Juan ▁Lav alle ▁led ▁a ▁military ▁coup ▁against ▁governor ▁Manuel ▁Dor re go . ▁He ▁executed ▁him ▁and ▁began ▁a ▁campaign ▁against ▁all ▁feder als , ▁supported ▁by ▁José ▁María ▁Paz ▁in ▁C ór dob a , ▁who ▁de posed ▁Juan ▁B aut ista ▁B ust os ▁and ▁took ▁similar ▁measures ▁against ▁feder als . ▁The ▁ran cher ▁Juan ▁Manuel ▁de ▁Ros as ▁organized ▁the ▁resistance ▁against ▁Lav alle , ▁forcing ▁him ▁out ▁of ▁government ▁and ▁rest oring ▁the ▁Legisl ature . ▁Paz ▁organized ▁the ▁Un itar ian ▁League ▁with ▁the ▁provinces ▁that ▁joined ▁him , ▁and ▁Ros as ▁signed ▁the ▁Federal ▁P act ▁with ▁Entre ▁R íos ▁and ▁Santa ▁Fe . ▁All ▁the ▁un itar ian ▁provinces ▁were ▁defeated ▁and ▁joined ▁the ▁P act , ▁and ▁became ▁the ▁Argent ine ▁Confeder ation . ▁Ros as ▁decl ined ▁a ▁new ▁term ▁as ▁governor ▁after ▁the ▁victory ▁over ▁the ▁un itar ian ▁league . ▁ ▁Ros as ▁left ▁Buenos ▁Aires ▁and ▁w aged ▁the ▁first ▁campaign ▁in ▁the ▁desert ▁in ▁the ▁south , ▁to ▁prevent ▁further ▁mal ones ▁from