Dictionary of National Biography, 1885-1900/Mackenna, John
MACKENNA, JOHN or JUAN (1771–1814), Chilian general, son of William Mackenna of Willville, co. Monaghan, by Eleanor, daughter of Philip O'Reilly of Ballymorris, was born at Clogher, co. Tyrone, on 26 Oct. 1771. He was fourth in lineal descent from Major John Mackenna, Jacobite high sheriff of co. Monaghan, who was killed by William's troops in an affair at Drumbanagher on 13 March 1689 (Harris, Life of William III). His education was entrusted to his kinsman, Alexander O'Reilly (1730-1794), a general in the Spanish service, who had been governor of Louisiana, 1767-9, commanded against Algiers in 1775, and was at the time of his death commander of the army of the Eastern Pyrenees. By O'Reilly's directions he left Ireland in 1784, entered the Royal Academy of Mathematics at Barcelona, and in 1787 was appointed cadet in the Irish corps of military engineers in the Spanish army. He served under O'Reilly during 1787–8 in the garrison at Ceuta, and during 1794 in the campaign of Rousillon against the French republic. His service was distinguished, but his promotion being delayed he determined to seek his fortune in the New World, and, in opposition to the wishes of his family, he sailed for Peru in October 1796. He carried with him recommendations to the Spanish viceroy, Ambrosio O'Higgins [q. v.], won his spurs as an engineer by reconstructing the important bridge of Rimac, and was on 11 Aug. 1797 appointed governor of Osorno. There, during a governorship which lasted until 1808, he strengthened the defences and built a road, in the face of great natural obstacles, from Osorno to Chiloé. In 1808 he was recalled and commissioned, as the most efficient military engineer in the country, to erect fortifications along the coast and take other measures of defence in view of the threatened French invasion. Though possessing the confidence of the Spanish government, Mackenna decided in 1810 to join the party of revolution, and was in the following year appointed provisional governor of Valparaiso. Shortly afterwards, as an adherent of José Miguel Carrera, the republican dictator, he became a member of the junta of Santiago, which held the supreme control of the revolutionary movement. He was also appointed commander-in-chief of artillery and engineers. This post he retained after his lack of docility had led to his expulsion from the junta by the Carreras; but failing to conceal his indignation at the slights put upon him he was arrested on 27 Nov. 1811, and banished to Rioja for three years from 27 Feb. 1812, on a charge of conspiring against the dominant faction. He appears, however, to have been indispensable, and was recalled early in 1813. He now rendered important service to the revolutionists. He made a valuable strategical map of the country and was appointed chief of the staff of the army of the south, destined to resist Pareja, who was advancing at the head of a powerful Spanish force to put down the insurrection. He took a prominent part in the campaign of April 1813, was promoted brigadier-general, and, on his return, military commander of Santiago. In the meantime he had entered into relations with Carrera's rival, Bernardo O'Higgins; and when, after the republican defeat on the banks of the Roble in October 1813, O'Higgins supplanted Carrera as commander-in-chief, Mackenna was appointed second in command. The care of the capital was entrusted to him, while O'Higgins guarded the frontiers. He succeeded in repelling the attacks of General Elorriaga, and even achieved some successes; but his chief, O'Higgins, though a brave soldier, manifested little strategic ability, and a military revolution restored Carrera to power on 23 July 1814. The dictator, who resented both Mackenna's ability and his co-operation with O'Higgins, arrested him in his bed on the night of his restoration and banished him to Mendoza. In the following November, while in Buenos Ayres, the exile encountered Luis Carrera, the dictator's brother; the result was a quarrel, followed by a duel, in which he was killed (21 Nov. 1814). He was buried in the cloister of the convent of Santo Domingo at Buenos Ayres, where an inscription was placed to his memory in 1855.
Mackenna married in 1809 Josefa Vicuña Larrain, by whom he had a daughter, Carmen; she married a cousin, Pedro Felix Vicuña, and had a son, Benjamin Vicuña Mackenna (1831–1886), a very distinguished Chilian publicist and historian (see a Life of him by P. P. Figueroa, Talca, 1885, and the same writer's Apuntes históricos sobre la Vida y las Obras de Don Benjamin Vicuña Mackenna, Santiago, 1886).
[Vida de D. Juan Mackenna (by his grandson, 1859); El Ostracismo del General D. Bernardo O'Higgins, Valparaiso, 1860, pp. 192 sq.; Diego Barras Arana's Historia general de Chile, 1891; Diccionario Biográfico General de Chile, 1889, pp. 319, 626; Appleton's Cyclopædia of American Biography, iv. 130; Brit. Mus. Cat., art. ‘Vicuña Mackenna;’ information kindly supplied by P. Mackenna, esq., of Cork.]