26 October 1771: John MacKenna was born in County Monaghan, Ireland on this day. He died 43 years later as one of the foremost men in Chile's struggle for Independence from Spain.
At an early age he was sent to Spain and joined the Irish Brigade of the Spanish Army. and joined the army fighting in Ceuta in northern Africa, under Lieutenant Colonel Luis Urbina, and was promoted to Second Lieutenant. In 1791 Mackenna resumed his studies in Barcelona and acted as liaison with mercenaries recruited in Europe. The following year he was promoted to Lieutenant in the Royal Regiment of Engineers. In the War of the Pyrenees against the French, Juan Mackenna fought in Rosselló under General Ricardos and there met the future liberator of Argentina, José de San Martín. For his exploits in defence of the Plaza de Rozas, he was promoted to captain in 1795.
In October 1796, Juan Mackenna left Spain for South America. He arrived in Buenos Aires and then travelled to Mendoza and to Chile across the Andes and then to Peru. Once in Lima, he contacted Ambrosio O'Higgins, another Irishman, at that time Viceroy of Perú, who named him Governor of Osorno and put him in charge of the reconstruction works for this southern Chilean town.
After the Declaration of Chilean Independence in 1810, he adhered to the Patriot side and was commissioned by the first Chilean government to prepare a plan for the defense of the country and oversaw the equipment of the new Chilean Army. At this juncture he trained the first military engineers for the new army.
The following year he was called to the defence committee of the new Republic of Chile, and in 1811 was appointed governor of Valparaíso. He was a firm ally of Bernardo O'Higgins, who appointed him as one of the key officers to fight the Spanish army of General Antonio Pareja. Mackenna's major military honour was attained in 1814 at the Battle of Membrillar, in which the general assured a temporary collapse of the royal forces.
As a reward for his victory, he was appointed commandant-general by Bernardo O'Higgins, but after a coup d'état led by Luis Carrera he was exiled to Argentina in 1814, when Carrera took over power. Juan Mackenna died in Buenos Aires late in 1814, after a duel with Luis Carrera.
In 2010, the Irish and Chilean Postal Service jointly issued stamps jointly celebrating Juan MacKenna and Bernardo O’Higgins for their parts in the Liberation of Chile.