After the capitulation of General Pio de Tristan in the battle of Salta, on 24 February 1813, the United Provinces' Army of the North gained the upper hand not only in northern Argentina, but also in southern Upper Peru (present-day Bolivia). At the same time, the royalists were experiencing a crisis of command, after the resignation of General José Manuel de Goyeneche for personal reasons. The Spanish garrisons reacted with panic after learning of Tristan's defeat and effected a massive withdrawal of their troops from Jujuy and Potosi towards Oruro, in central Upper Peru. During the early days of May the Army of the North reached Potosi, and a forward screen force of about 500 men was deployed along the route to Oruro. These troops, composed of a cavalry regiment of Dragones (Dragoons), w