Upper Peru, area of operations of the Army of the North sent from Buenos Aires

The Army of the North (Spanish: Ejército del Norte), contemporaneously called Army of Peru, was one of the armies deployed by the United Provinces of the Río de la Plata in the Spanish American wars of independence. Its objective was freeing the Argentine Northwest and the Upper Peru (present-day Bolivia) from the royalist troops of the Spanish Empire. It was headed by Hipólito Vieytes (1810), Juan José Castelli (1810–1811), Juan Martín de Pueyrredón (1811–1812), Manuel Belgrano (1812–1814), José de San Martín (1814), José Rondeau (1814–1816), Manuel Belgrano (1816–1819) and Francisco Fernández de la Cruz (1819-1820).

The offensive operations started in 1810 and ended in 1817, with the defeat of the forces commanded by Gregorio Aráoz de La Madrid at the battle of Sopachuy, the last attempt to advance into Upper Peru. Since then, only defensive operations on the Northern frontier were carried on, as the offensive had been transferred to the Army of the Andes, commanded by José de San Martín, who devised the strategy of reaching the main royalist stronghold, Lima, through Chile and the Pacific Ocean. In 1820 the Army of the North was summoned to intervene in the internal strife between the central government in Buenos Aires and the Federal League provincial caudillo leaders. Shortly after, the Arequito Revolt led by the independentist veterans who refused to fight a civil war instead of an independence war, effectively ended the existence of the Army of the North.

During the War of the Confederation, between Chile, Argentina and the Peru-Bolivian Confederation, a new military corps received the name of Army of the North (1837) under the command of Alejandro Heredia. The Army would disband itself without conducting any major operations after the uprising known as North Coalition and the 1838 assassination of Heredia. The war ended in 1839 with a decisive Chilean victory at the Yungay, so the Peruvian-Bolivian army retreated from Argentine territory.