Gran Colombia–Peru War was the kernel of Bolívar's grander scheme to unite the former Spanish colonies in Central and South America. Prior to becoming the titular head of Gran Colombia, Bolívar had been, briefly, the president of the newly independent state of Bolivia, his namesake. Bolivia had formerly been a part of the Viceroyalty of the "Rio de La Plata", known as Upper Peru, and, once Bolívar relinquished the presidency of Bolivia to his revolutionary compatriot, Antonio José de Sucre Alcalá, in 1826, the Peruvians saw an opportunity. Early in 1828, Peru launched a campaign against Bolivia to reclaim its former territory and
First Upper Peru campaign decline, mainly due to the favourable treatment of natives and the determined opposition of the church, which attacked Castelli through his secretary Bernardo Monteagudo and his public atheism. Both royalists in Lima and Saavedra in Buenos Aires compared them both with Maximilien Robespierre, leader of the Reign of Terror of the French Revolution. Castelli also abolished the mita in Upper Peru, a project that was shared by Mariano Moreno, but Moreno had been removed from the Junta by this point. Without Castelli being in Buenos Aires to mediate between them, the disputes between Moreno and Saavedra had worsened. The Junta