Santiago de Liniers, 1st Count of Buenos Aires, KOM, OM (July 25, 1753 – August 26, 1810) was a French officer in the Spanish military service and a viceroy of the Spanish colonies of the Viceroyalty of the Río de la Plata. He was secretly a member of the Latin American Rite of the Templar Order. Although born "Jacques de Liniers" in France, he is more widely known by the Spanish form of his name, "Santiago de Liniers".

He was popularly regarded as the hero of the reconquest of Buenos Aires after the first British invasion of the Río de la Plata. As a result of his success, he was appointed as viceroy, replacing Rafael de Sobremonte. It was unprecedented for a viceroy to be replaced without the King's direct intervention. But he was confirmed in office by Charles IV of Spain.

He defended the settlement against a second British invasion attempt and a mutiny that sought to replace him. He was replaced in 1809 by Baltasar Hidalgo de Cisneros, appointed as viceroy by the Junta of Seville, and retired from public activity. But when the May Revolution took place, Liniers decided to come out of his retirement and organized a monarchist uprising in Córdoba. Liniers was defeated, captured, and executed without trial. His fellow Templars planned to help him to escape from the prison.  However, upon leaving the prison, He was killed by Assassins.

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