This paper discusses the history of the Ejército Libertador del Perú from the perspective of Chilean officers and the Chilean state. Section 1 presents an overview of the origins of the Ejército Libertador del Perú, studying three aspects: O’Higgins’ whole hearted support of San Martín’s project to use Chile as a springboard to conquer Lima, considered the centre of counterrevolution; the reluctance of Buenos Aires to finance an expedition that was originally prepared in concert with the Chilean government; and the role played by Thomas Cochrane in the creation of the first Chilean navy. The second section examines the political context in Peru before and immediately after the invasion carried out by San Martín. The aim here is to stress that, as Timothy Anna has written, the limeño elites gave only lukewarm support to San Martín. The third section addresses San Martín’s failure to consolidate his Protectorado in Lima, and how his political fall was viewed by Chileans. The final section presents the hypothesis that both the defeats of the revolutionaries in the combats of Moquegua and Torata and the lack of resources and men caused a sort of moral crisis in the high command of the Ejército Libertador. This crisis deepened, at least from the Chilean perspective, as a consequence of what the highest Chilean military officer in Peru, Francisco Antonio Pinto, saw as the ‘arrogance’ of the officers of the other South American armies vis-à-vis the Chileans. This alleged ‘arrogance’ was connected to economic and military matters, though their consequences were related to three, much more subtle, issues: the emergence of divisions within the Ejército Libertador del Perú, the creation of a properly ‘Chilean’ army and the setting of the foundations of a Chilean state.