In 1814 the royalist forces, based in Peru, took advantage of internal dissensions among the various factions of the nationalist movement in Chile to mount an invasion. The 5,000-man royalist army defeated the 1,800-man nationalist force, led by Bernardo O'Higgins Riquelme and Juan José Carrera, in the Battle of Rancagua on October 2, and the remnants of the routed army (300 men) fled to Mendoza in present-day western Argentina.

The leaders of the United Provinces of the Río de la Plata, a short-lived (1813-26) federation of the provinces that had made up the Viceroyalty of the Río de la Plata, realized that their position remained insecure following independence in 1816 so long as Chile and Peru remained bastions of Spanish power. It was decided, therefore, to send an expeditionary force, named the Army of the Andes, across the mountains to confront the royalists. The combined Argentine-Chilean Army of the Andes, under the joint command of O'Higgins and José de San Martín, set out from San Juan in northern Argentina on January 12, 1817. The army consisted of 2,795 infantry, 742 cavalry, and 241 artillerymen, who carried with them twenty-one guns and sufficient arms to equip a force of 15,000. Crossing the Andes at Paso de Uspallata and Paso de los Patos, this sizable army took the royalist forces in Chile completely by surprise. With only half of the total royalist strength of approximately 4,000 available to meet the invaders (the other 2,000 were deployed mainly in defense of the southern frontier), the royalists suffered a decisive defeat at Chacabuco, northeast of Santiago, on February 12, 1817. By the end of 1817, the Chilean Army (Ejército de Chile), consisting of 5,000 soldiers and officers, had been established. Despite reverses at Talcahuano on December 16, 1817, and at Cancha Rayada on March 19, 1818, the allied army swept to final victory at Maipú on April 5, 1818. Peru, however, remained a royalist stronghold, separated from Chile by the Atacama Desert and approachable only by sea (see Wars of Independence, 1810-18 , ch. 1).

Chile had first attempted to form a navy in 1813, when the United States-built frigate Perla and the brigantine Potrillo were acquired to break the Spanish blockade of Valparaíso. However, royalist elements succeeded in bribing the mercenary crew of the Perla, with the result that both vessels fell into the hands of the Spaniards. The official history of the Chilean Navy (Armada de Chile) dates from February 26, 1817, when the brigantine Águila was acquired by the nationalists. Armed with sixteen guns, the Águila was commissioned as the first naval vessel of the Republic of Chile, under the command of Raimundo Morris, an Irish mercenary and former lieutenant in the British Royal Navy. Under the overall command of Manuel Blanco Encalada, the first rear admiral of the Chilean Navy, the tiny fleet rapidly tripled in size with the capture of the Spanish merchant vessel San Miguel and the recapture of the Perla.e68 m> Additional vessels were added by purchase, the arming of merchant ships, and further captures from the enemy. With those acquisitions, the revolutionary fleet consisted of a small ship of the line, two large frigates, and four corvettes. In 1818 the Naval School (Escuela Naval) was established, later named the Arturo Prat Naval School (Escuela Naval Arturo Prat), after Arturo Prat Chacon, naval hero of the War of the Pacific. Then, on November 28, 1818, the famous British admiral Thomas Alexander Cochrane (Lord Dundonald), who had been forced to resign from the Royal Navy following a financial scandal, assumed command of the revolutionary fleet from Blanco Encalada. Within two years, Cochrane's fleet had established control of the sea, and it was then possible to prepare for an amphibious invasion of Peru. With the help of the Chilean fleet, the allied army, headed by San Martín, liberated Lima on July 9, 1821, and the independence of Peru was declared on July 28.

When Cochrane left Chile in 1823, Blanco Encalada reassumed command of the navy, which was reequipped in 1824. The allies--now joined by a substantial force from a republic known as Gran Colombia (consisting of present-day Colombia, Panama, and Venezuela) and led by Simón Bolívar Palacios and Antonio José de Sucre--scored successive victories at Junín and Ayacucho in August and December 1824, respectively. That year Blanco Encalada fought in Callao, Peru, under Bolívar's command. Meanwhile, despite their defeats on the Chilean mainland and in Peru, the royalists had continued to hold out on the Isla de Chiloé, off the southern Chilean coast, and were only finally defeated in 1826 after two amphibious campaigns by Blanco Encalada and several nationalist reverses.

Diego Portales Palazuelos, Chile's main political strongman from 1830 to 1837, reorganized and streamlined the army, putting it on a firm basis with three infantry battalions, two regiments of cavalry, a squadron of hussars, and a regiment of artillery. The General Bernardo O'Higgins Military Academy (Escuela Militar "General Bernardo O'Higgins"), founded by O'Higgins on March 16, 1817, was also reorganized. It provided an uninterrupted flow of professional officers from 1832 onward. Portales also reestablished the civic militias, which were important elements in the defense of cities and towns during the colonial period. Over the next decades, these militias, whose officers were appointed and removed by the ministers of interior, proved to be a significant countervailing power to that of the army. They thus contributed to the stability of the constitutional government. During the civil wars of 1851 and 1859, the authorities relied on the combination of civic militas and some army units to defeat the insurrectionists.

Data as of March 1994