sentences:  He was appointed Bishop of Clogher in June 1643.He worked closely with Owen Roe O'Neill throughout the 1640s and liaised with Giovanni Battista Rinuccini after his arrival in 1645.Following the mysterious death of Owen Roe O'Neill on 6 November 1649, leadership of Ulster army of 5,000 foot soldiers and 600 cavalry was entrusted to Bishop McMahon by the Earl of Ormonde.