LAS HERAS, Juan Gregorio de (las-air'-as), South American soldier, born in Buenos Ayres, 11 July, 1780; died in Santiago, Chili, in February, 1866. He engaged in business till the age of twenty-six, when he enlisted in the army, taking part in the struggles of 1806-'7 against the English. In 1808 he became sergeant of hussars, and, when independence was declared in 1810, he acted with the patriots, was appointed captain of militia in Cordova, and in 1812 became commander of the garrison of that city. In 1813 he offered to accompany the auxiliary Argentine division, of which he became second in command. After the battle of Cuchacucha he attained the rank of colonel, and after the defeat of Rancagua. 2 October, 1814, he retired in good order and twice repulsed the enemy. Afterward he was employed in Mendoza in the organization of the Army of the Andes. In 1817, leading one column by the pass of Uspallata, he commanded in the battles of Potrerillos, Guardia, and Villa de los Andes. Together with the forces of General San Martin he took part in the battle of Chacabuco, 12 February, 1817, and immediately afterward was sent to the south, gained the victories of Curapalihue, Vegas de Talcahuano, and Oavihm, and was present at both of the sieges of Talcahuano under the orders of General O'Higgins. In 1820 he was chief of staff of the liberating army of Peru, and in the same year was promoted brigadier by the Argentine government, and general of division by the Chilian government. In Peru he had the command of the siege of the castles of Callao and received the title of grand marshal. After retiring from Peru he went to the Argentine Republic, where he was elected governor of the province of Buenos Ayres in May, 1824. During his government the congress of the united provinces met on 16 December, 1824, and on the restoration of the confederation and the election of Rivadavia to the executive, Las Heras delivered the government to him, 7 March, 1825, and in 1826 returned to Chili. He was deprived of his rank on account of the civil disturbances of 1830, but it was restored by congress in 1842 and by the Argentine congress in 1855. From 1862 till the time of his death he was inspector-general of the army.