LUAIN -- On Oct. 26, 1771, John (Juan) MacKenna, who would rise to fame in South America, was born in Clogher, County Tyrone. MacKenna was related to Gen. Alexander O'Reilly, of the Spanish army, and O'Reilly helped MacKenna get established in Spain. In 1787, MacKenna was appointed a cadet in the Irish Brigade of the Spanish army and fought with them in Ceuta in northern Africa. After returning t…