Spanish General Diego O'Reilly Is Defeated by Peruvian Revolutionaries

Diego O’Reilly, (b. Ireland, c. 1775 – d. high seas, 1821), an Irishman born in Spain, and was a general in the Spanish Army who served in South America during the period of Spanish American War of Independence of Peru.

In 1820, during the Peruvian War of Independence, O’Reilly led Spanish royalist forces against the revolutionary forces led by José de la Riva-Agüero and José de San Martín. The decisive battle was the Battle of Cerro de Pasco, fought on December 06, 1820.

Battle of Pasco

On 6 December 1820, Arenales led troops into the Battle of Pasco (es), using thick snowfall to launch a surprise attack. Arenales defeated the royalist troops commanded by Diego O’Reilly, capturing O’Reilly and incorporating prisoners into his own forces.

The Spanish forces, commanded by O’Reilly, suffered a significant defeat in this battle at the hands of the independence forces. This victory by the Peruvian revolutionaries, under the leadership of Riva-Agüero, was an important moment in the broader context of the South American wars of independence.

Upon news that royalist forces were defeated by Arenales’ expedition, the city of Huánuco called for a town meeting on 9 December 1820.

Don Eduardo Lúcar y Torre, a colonel of the royalist army, allowed the citizens of Huánuco to vote on whether or not to join Arenales’ cause, with the majority voting to join the patriot movement.

On 15 December 1820, Huánuco declared independence and because of their assistance, Lúcar y Torre was named Mayor of Huánuco and José Figueroa was named the commander of arms.

The defeat at Cerro de Pasco weakened Spanish control over Peru, opening the way for further advances by the revolutionary forces led by José de San Martín, who would go on to play a crucial role in the liberation of Peru from Spanish rule.