In 1845, Britain and France intervened against Rosas to restore commerce to normal levels in the region. Their efforts proved ineffective and, by 1849, tired of the war, both withdrew after signing a treaty favorable to Rosas. It appeared that Montevideo would finally fall when an uprising against Rosas, led by Justo José de Urquiza, governor of Argentina's Entre Ríos Province, began. The Brazilian intervention in May 1851 on behalf of the Colorados, combined with the uprising, changed the situation and Oribe was defeated. The siege of Montevideo was lifted and the Guerra Grande finally came to an end. Montevideo rewarded Brazil's support by signing treaties that confirmed Brazil's right to intervene in Uruguay's internal affairs.