 Complete the following phrase:  By June 1813 Belgrano set up a base in Potosí with an army of 2,500 men, to prepare an attack on Upper Peru. Goyeneche moved to Oruro and resigned, being replaced by Joaquín de la Pezuela. Belgrano administrated the zone and tried to revert the bad impression left by the previous campaign of Juan José Castelli. Belgrano initiated good relations with the natives as well. Belgranos plan was to attack the royalists from the front and the sides, with the aid of the armies of Cárdenas and Zelaya. Both armies were near 3,500 men. However, the royalists obtained an important advantage by defeating Cárdenas and getting possession of his papers, which gave them insight into the patriotic plans. Belgrano was taken by surprise at 