War of the Confederation

The war's immediate origins lay in the rapid consolidation of the Peru–Bolivian Confederation under General Andrés de Santa Cruz following the defeat and execution of the Peruvian caudillo Felipe Salaverry in 1836^[1]. Santa Cruz's victory in what is known as the Salaverry–Santa Cruz War gave him personal command of a unified polity stretching from the Bolivian altiplano to the Peruvian Pacific coast — a bloc that, by population, territory, and military potential, represented the largest power in Andean South America. It was this sudden reconfiguration of the regional balance, rather than any single act of aggression, that convinced both Santiago and Buenos Aires that armed intervention was necessary^[2].

For Chile, the geopolitical alarm was direct and specific. A consolidated Peru–Bolivian state would command Pacific ports and naval resources on Chile's northern flank, threatening commercial routes that Chilean merchants and the Chilean state depended upon. Chilean strategists and the government of Joaquín Prieto also received Peruvian émigré agitation — soldiers and politicians hostile to Santa Cruz who sought external support for a restoration — lending the intervention a pretext of legitimacy beyond pure self-interest^[3]. Chilean statesmen calculated, moreover, that a confederation possessing both Atlantic-facing Bolivia and Pacific-facing Peru would be structurally difficult to contain once it matured, making early action preferable to later confrontation.

The Argentine Confederation shared the Chilean unease but arrived at belligerence through a somewhat different path. Buenos Aires had its own territorial and political frictions with Bolivia along their Andean frontier, and the Rosas government regarded Santa Cruz's ambitions with deep suspicion^[4]. Crucially, the Argentine Confederation and Chile waged their respective campaigns against the confederation independently rather than as a coordinated alliance — a fact that shaped the conduct of the war as much as its causes, reflecting that the two states shared an adversary but not a joint strategic vision^[5].

Underlying these geopolitical calculations was an ideological dimension common to the post-independence Andean republics: the acute sensitivity of new states to any arrangement that appeared to reverse the territorial settlement achieved after independence. Santa Cruz's project recalled, at least in the minds of its opponents, the colonial jurisdictions of the old Viceroyalty of Peru. To Chilean and Argentine republicans alike, the confederation was a dangerous anomaly — an expansionist personal state built on military conquest of a neighboring republic — and dismantling it could be framed as a defense of the Westphalian norms that the newly sovereign states of South America were attempting to establish^[6]. Incidents involving Chilean vessels and alleged Confederation interference in Chilean internal affairs provided the proximate diplomatic justifications, but the structural fear of a dominant Andean hegemon was the force that made war the preferred instrument of policy for both Santiago and Buenos Aires^[7].

The dissolution of the Chilean-led coalition's campaign against the Peru–Bolivian Confederation culminated in the decisive Chilean victory at Portada de Guías in 1839, which broke Confederate military resistance and forced Andrés de Santa Cruz into exile^[1]. The Confederation itself, barely three years old, collapsed immediately thereafter: the union of North Peru, South Peru, and Bolivia that Santa Cruz had constructed as a reforming federal state was dissolved, and the constituent territories reverted to separate republican governments. No single comprehensive peace treaty governed the settlement; rather, the Confederation's dissolution was a political fact enforced by military presence, and the successor states negotiated their respective relationships with Chile and with one another over the following years^[2].

For Chile, the war confirmed the political ascendancy of the conservative-authoritarian order consolidated under the Constitution of 1833 and the government of Joaquín Prieto^[3]. The successful prosecution of a foreign war, including the projection of naval and land power northward — demonstrated at engagements such as the Battle of Casma at sea and the overland campaign through Peru — reinforced the institutional credibility of the Chilean army and the centralized state apparatus^[4]. The war also established Chile as the preeminent military power on the Pacific coast of South America, a position that would shape regional politics for the remainder of the nineteenth century.

The Argentine Confederation's involvement produced far more ambiguous results. Buenos Aires had joined the war against Santa Cruz primarily out of fear that a consolidated Peru–Bolivian state would back internal Argentine opponents of Juan Manuel de Rosas, and indeed Santa Cruz had provided material support to Argentine unitarians^[5]. The Confederation's military operations on the northern front were substantially less effective than Chile's, and Buenos Aires derived little direct territorial or diplomatic gain from the Confederation's collapse. The episode nonetheless reinforced Rosas's political dominance domestically by allowing him to frame the war as a defense of Argentine sovereignty against external interference^[6].

The geopolitical consequences for the Andean republics were lasting. Bolivia, stripped of its union with Peru and of Santa Cruz's leadership, entered a prolonged period of political instability and military coups that would characterize much of its nineteenth-century history^[7]. Peru likewise underwent a turbulent succession of governments in the immediate postwar years, as the factions that had opposed the Confederation from within — represented militarily by the Restoration Army — competed for dominance. The war had been fought partly by Peruvians against Peruvians, and the wounds of that internal division did not heal quickly^[8].

What the war did not resolve was the underlying question of Andean political integration. Santa Cruz's Confederation had represented one answer — coercive but coherent — to the fragmentation left by independence. Its destruction settled nothing about the long-term relationship between Bolivia and Peru, the viability of small Andean states in an era of growing regional competition, or the boundary questions that would continue to generate friction among Chile, Bolivia, and Peru. Those unresolved tensions would re-emerge with far greater violence in the War of the Pacific four decades later, in which the same geopolitical fault lines — Pacific littoral control, Bolivian access to the sea, Peruvian territorial integrity — became the stakes of a far more destructive conflict^[9].