MacMahon (Ennis), Bernard (c.1680–1747), catholic archbishop of Armagh, was born in Co. Monaghan and educated at the Irish college in Rome. He was consecrated bishop of Clogher in 1709, and with a number of other bishops took measures to curtail the growth in the numbers of clergy and to bring the regular clergy under secular control. He opposed efforts by the canons regulars to enforce papal bulls, issued by Benedict XIII in 1729, declaring four of their number abbots. With the archbishops of Dublin and Tuam he petitioned Cardinal Corsini to rescind these creations. The petition was partly successful.
In 1738 he was translated to Armagh. He assumed the name ‘Ennis’ as an alias and lived at Ballymascanlan; a local poet, Patrick O'Prunty, composed a Gaelic poem in his honour. In 1741 MacMahon was forced to flee his residence to escape ‘four magistrates armed with warrants’ who were searching for him at the instigation, it appeared, of ‘an unworthy person to whom I have refused a parish’ (Wall, 33). The same year he wrote to Propaganda Fide on the topic of the charter schools, through which the Incorporated Society for Promoting English Protestant Schools sought to instruct catholic children in English and the tenets of the state religion. The rich having been lost to the church, MacMahon warned, it now seemed likely that the poor would follow. He suggested that Propaganda support Irish clergy, through revenues from foreign benefices, to counteract the schools. His recommendations were well thought of by Benedict XIV, as were his suggestions concerning the need to curtail the growth in clerical numbers, especially among the regulars.
In 1744, as a result of the renewal of war with France and fears of a Jacobite invasion, information on MacMahon was communicated to Dublin, but he escaped interference. He died 27 May 1747 and was buried in the churchyard of Edergole, Co. Monaghan; a tombstone was erected over his grave in 1750 by his younger brother Roger.