Gaspar Vigodet in Montevideo, replacing José Rondeau and making the Oriental leader José Gervasio Artigas an enemy. Alvear was a leader of the constituent Assembly of the year 1813 and, goaded by political ambition, succeeded in establishing a Unitarian (centralizing) form of government, having his uncle Gervasio Antonio de Posadas named Supreme Director (chief executive). In early 1814, Alvear was appointed commander in chief of the forces defending the capital. A few months later, he replaced General José Rondeau as commander in chief of the army besieging Montevideo, the last bastion of Spanish power in the River Plate, which was defended by 5,000 troops. In late June 1814, as news that Ferdinand VII had recovered the crown of Spain, Alvear managed to force the surrender of the Spanish troops in Montevideo. It was the biggest victory for the cause of independence since 1810. He was only 25 and the most successful general of the revolution. He returned to Buenos Aires to claim his laurels but a revolt forced him back to the Banda Oriental. After a quick and decisive campaign, his forces defeated the caudillos that opposed the government. At the end of 1814 Alvear was named commander of the Army of the North, but he lacked of support from Posadas, and his unpopularity among the troops, and other disagreements—including a project for a constitutional monarchy that he sent to Europe to be negotiated by Manuel Belgrano, that was fiercely opposed by the League of Free Peoples—made him return to Buenos Aires. On January 9, 1815, at 25 years of age, he was chosen to replace his uncle Posadas as Supreme Director. Having neither the support of the troops nor sufficient influence on the people of the hinterland provinces, Director Alvear then attempted to come to an alliance with Artigas, to whom he offered the independence of the Banda Oriental (current Uruguay). In exchange, Artigas would withdraw his army from the Argentine Littoral. But Artigas declined the offer, and Alvear sent troops to occupy the area. At this time he was in correspondence with the British ambassador, Viscount Strangford in Rio de Janeiro, in order to ask for a British intervention. Following a mutiny among his troops, and under pressure from the Cabildo, Alvear resigned on April 15, and left the country. He was in exile in Rio de Janeiro until 1818. In May of that year, he moved to