The breakup of the old Viceroyalty of the Río de la Plata during the 1810s eventually resulted in the emergence of independent nations of Paraguay, Bolivia and Uruguay in the northern portion of the Viceroyalty, while its southern territories coalesced into the United Provinces of the Río de la Plata. Rosas planned to restore, if not all, at least a considerable part of the former borders of the old Viceroyalty of the Río de la Plata. He never recognized the independence of Paraguay and regarded it a rebel Argentine province that would inevitably be reconquered. He sent an army under Manuel Oribe who invaded Uruguay and conquered most of the country, except for its capital Montevideo that endured a long siege starting in 1843. When pressed by the British, Rosas declined to guarantee Uruguayan independence. In South America, all potential foreign threats to Rosas's plans of conquest collapsed, including Gran Colombia and the Peru–Bolivian Confederation, or were troubled by internal turmoil, as was the Empire of Brazil. To reinforce his claims over Uruguay and Paraguay, and maintain his dominance over the Argentine provinces, Rosas blockaded the port of Montevideo and closed the interior rivers to foreign trade.