Although Buenos Aires had suffered a difficult period in its war for independence, its prospects were improving by 1812. Even though the defeats of Manuel Belgrano during the Paraguay campaign and Juan José Castelli in the first Upper Peru campaign had generated a political crisis, Belgrano's victory at the Battle of Tucumán had given new hope to the revolution, which would be strengthened shortly afterwards with the victory at the Battle of Salta. Montevideo, capital of the Viceroyalty of the Río de la Plata since the May Revolution, was under siege by both an army from Buenos Aires led by José Rondeau and a Uruguayan one led by José Gervasio Artigas. The city, however, maintained its naval supremacy over Buenos Aires and their ships raided the coasts of the Paraná and Uruguay rivers to gather supplies, despite the siege. Montevideo organized a navy to destroy the gun batteries at Rosario and Punta Gorda, two population centres along the Paraná, but were prevented from doing so as Buenos Aires dismantled them knowing that they could not be defended.