The fall of Montevideo eliminated the royalist menace from the Banda Oriental and meant the actual end of the Spanish Viceroyalty of the Río de la Plata. Soon afterwards, William Brown was awarded the rank of admiral, and Carlos María de Alvear, who was put in charge of the siege of Montevideo just a few days before the surrender of the city, succeeded his uncle Gervasio Posadas as the Supreme Director of the United Provinces, on January 11, 1815. Alvear, however, was resisted by the troops, so he was quickly replaced, on April 21, by Ignacio Álvarez Thomas through a mutiny. Álvarez Thomas then appointed Alvear as general of the Northern Army, in replacement of José Rondeau, but the officiality did not recognize this and remained loyal to Rondeau.