San Martín: Across the Andes, 1817

Mendoza became the crucial headquarters for the preparations before the crossing. Its citizens supported the troops by making gunpowder and ammunition, and they even learned to make cannons. Today a huge memorial monument to the Army of the Andes crowns the Cerro de la Gloria, a small hill in General San Martín Park. It was begun in 1911 and inaugurated on 12 February 1914, an anniversary of the Battle of Chacabuco, and it is the best place to begin the story.

Visitor guidance: The monument stands at the top of the hill in General San Martín Park.

On the morning of 19 January 1817, San Martín and his army set out from their base camp, El Plumerillo. He crossed with 4,000 men and ultimately lost one-third of them during the trek. The troops lived on valdiviano, a regional dish of dried meat, sliced raw onion, potatoes and boiling water, and soldiers were assigned to carry the food.

Location precision: The pin marks El Plumerillo in Las Heras; the exact site of the camp is not given in the sources.

The main division, led by San Martín, Miguel Estanislao Soler and Bernardo O'Higgins, went through the Pass of Los Patos. Between 19 and 25 January 1817 a column of 3,200 men left El Plumerillo this way. A supply depot at Los Manantiales, 3,200 m up in San Juan, was set up to feed men and animals for twenty days. At the Espinacito ridge, 4,476 m above sea level, the army reached the highest point of the expedition.

Location precision: Los Patos names several passes and the army's exact track is only partly known; the pin marks the Patos valley area.

The secondary division, under Juan Gregorio de Las Heras, took the more southerly Uspallata Pass. It reaches about 3,830 m, and in 1817 it was used by the Army of the Andes to cross the Andes. On the same pass, at 3,832 m on the border between Argentina and Chile, stands Christ the Redeemer of the Andes, unveiled on 13 March 1904 to celebrate a peaceful settlement of a border dispute between the two countries.

On 12 February 1817 San Martín divided his troops in two, with Soler on the right and O'Higgins on the left. By the end, 500 royalist soldiers were dead and 600 taken prisoner, while the Army of the Andes lost only twelve men in battle. The next day, 13 February, San Martín, O'Higgins and the army entered Santiago after crossing 500 kilometres of mountains. San Martín then declined the governorship, and O'Higgins became Supreme Director of Chile.

Location precision: The pin marks the Chacabuco area; the fighting spread over a valley and its ranch.

The final battle was fought near Santiago on 5 April 1818, and the patriots under San Martín effectively destroyed the Spanish forces. About 1,500 Spaniards died and 2,289 were captured. After the battle O'Higgins and San Martín embraced, remembered as the "Abrazo de Maipú". Every 5 April a joint civil-military parade is held in Maipú to mark the victory.

Location precision: The pin marks the Maipú area where the battle occurred; the fighting covered a wider field.