ig as ▁wished ▁to ▁defend ▁these ▁ide als ▁in ▁the ▁Eastern ▁Bank . ▁At ▁the ▁beginning ▁of ▁April ▁he ▁returned ▁to ▁his ▁country ▁with ▁approximately ▁ 1 8 0 ▁men ▁provided ▁by ▁the ▁Government ▁of ▁Buenos ▁Aires ; ▁on ▁April ▁ 1 1 , ▁he ▁issued ▁the ▁Mer cedes ▁Pro clam ation , ▁assumed ▁control ▁of ▁the ▁revolution ▁and ▁on ▁May ▁ 1 8 ▁defeated ▁the ▁Spanish ▁in ▁the ▁Battle ▁of ▁Las ▁P ied ras . ▁He ▁then ▁began ▁the ▁sie ge ▁of ▁Monte video ▁and ▁was ▁acc laimed ▁as ▁The ▁First ▁Chief ▁of ▁the ▁" Ori ent als " ▁( the ▁first ▁names ▁of ▁current ▁Uruguay ▁being ▁Band a ▁Oriental ▁( E astern ▁Bank ) ▁and ▁later ▁Provin cia ▁Oriental ▁( E astern ▁Province ), ▁Uruguay ans ▁thus ▁refer ▁to ▁themselves ▁as ▁' Ori ent ales '). ▁ ▁He ▁soon ▁turned ▁against ▁the ▁government ▁of ▁the ▁United ▁Provin ces ▁of ▁the ▁Río ▁de ▁la ▁Pl ata ▁ ▁and ▁in ▁ 1 8 1 4 ▁he ▁organized ▁the ▁Un ión ▁de ▁los ▁P ue bl os ▁Lib res ▁( Union ▁of ▁the ▁Free ▁Pe op les ), ▁of ▁which ▁he ▁was ▁declared ▁Prote ctor . ▁In ▁the ▁following ▁year , ▁as ▁a ▁federal ist , ▁he ▁liber ated ▁Monte video ▁from ▁the ▁central izing ▁control ▁of ▁the ▁" Unit ari ans " ▁from ▁Buenos ▁Aires , ▁and ▁in ▁ 1 8 1 5 ▁declared ▁the ▁Liga ▁Federal . ▁ ▁In ▁this ▁Congress ▁Art ig as ▁rat ified ▁the ▁use ▁of ▁the ▁flag ▁created