Crossing of the Andes: Many soldiers of Juan Gregorio de las Heras are captured during the Action of Picheuta.

The action of Picheuta was a military engagement that took place on January 24, 1817, during the Crossing of the Andes.

The column led by Juan Gregorio de las Heras was still crossing the mountain range, being 50 kilometers away from the Uspallata Pass. A royalist task force led by Miguel Marquelli, composed of three officials and fifty soldiers, surprised the patriots at Picheuta, which was defended by five soldiers, many privates and a corporal from the battalion N 11. Marquelli had orders to cross the Uspallata on a reconnaissance mission.

The royalists surprised the patriots with an attack from the left flank. Half the forces of Las Heras was captured and taken prisoners, and the others fled to warn the bulk of the Army of the Andes of the nearby royalist presence. This led to the Battle of Potrerillos the following day.

The Crossing of the Andes (Spanish: Cruce de los Andes) was one of the most important feats in the Argentine and Chilean wars of independence, in which a combined army of Argentine soldiers and Chilean exiles invaded Chile leading to Chile's liberation from Spanish rule. The crossing of the Andes was a major step in the strategy devised by José de San Martín to defeat the royalist forces at their stronghold of Lima, Viceroyalty of Perú, and secure the Spanish American independence movements.Setting out from Mendoza – then part of the Province of Cuyo – in January 1817, their goal was to enter royalist-held Chile without being noticed, through unexpected paths, so as to attack the royalist forces by surprise. The ultimate objective was the liberation of Chile from Spanish rule with Argentine forces. Led by José de San Martín, the crossing took 21 days.