On 12 February 1817 the Army of the Andes under José de San Martín, with the Chilean patriot Bernardo O'Higgins leading one of its divisions, defeated a royalist force under Brigadier Rafael Maroto at Chacabuco, north of Santiago. The patriots had only just crossed the Andes from Argentina. The victory opened the road to Santiago and began the end of Spanish rule in Chile, sealed the following year at Maipú. O'Higgins became Supreme Director of Chile.
Over the Andes
After Argentina declared its independence in 1816, José de San Martín turned to Chile, which was still under Spanish control. In January 1817 he led his Army of the Andes over the mountains, joined by O'Higgins. The crossing was costly. Britannica says San Martín set out with about 5,000 men on a difficult 20-day march and lost about 2,000 of them to cold and altitude. HISTORY.com says that as much as one third of his 6,000 men died and more than half of his horses were lost. Even so, the patriots arrived in Chile with more men than the royalists could gather in time.1
The plan of attack
Britannica says San Martín managed to surprise the royalists. Brigadier Rafael Maroto could bring only part of the royalist army to the hills of Chacabuco. Britannica puts his force at about 1,500 men.2
San Martín split his army into two divisions, which marched for the heights during the night of 11 to 12 February. O'Higgins was to come down the main road and engage the royalists in front, while Miguel Estanislao Soler took a longer path over the hills to the right to fall on their left flank. The Chilean Academy of Military History, following the 19th century historian Diego Barros Arana, gives Soler about 2,000 men and O'Higgins fewer than 1,400.3
O'Higgins attacks early
O'Higgins reached the enemy first, while Soler's column was still on its long and narrow path. Instead of waiting, he attacked. His first assault was thrown back.4
Accounts differ on what turned the battle. Britannica credits a grenadier charge led by San Martín himself, which gave O'Higgins time to recover and strike the Spanish flank. HISTORY.com, like Barros Arana, stresses the arrival of Soler's division on the royalist flank and rear, which cut off the retreat. The royalist line broke, and by about two in the afternoon the battle was over.5
Losses and what followed
Royalist losses were heavy: more than 500 killed and more than 600 taken prisoner, according to Barros Arana. Patriot losses were light, but they are counted differently. HISTORY.com gives about a dozen killed in the battle and about 120 more who later died of their wounds; Barros Arana puts the patriot killed and wounded together at no more than 150.6
The road to Santiago lay open. The patriots entered Santiago, and San Martín declined power in Chile in favor of O'Higgins, who became Supreme Director. On 12 February 1818, the first anniversary of the battle, the independence of Chile was proclaimed at Talca. The war was decided later that year at the Battle of Maipú.7 › Battle of Maipú, 1818
