Their perseverance was rewarded with three scores on the trot, a Callum Boland free and a brace of points from play by accurate corner-forward Darragh Corbett.
While Cnoc Mhuire faded in the final quarter, they had already done enough to move into
the next round of the championship and had the last say with time almost up when substitute Michael Cullen scored the third goal as his team ran out rather flattering eight points winners in the finish.
CNOC MHUIRE: Gavin Kelly (Northern Gaels); Thomas Fox (Northern Gaels), Shane McKeon (Northern Gaels), Anthony Baxter (Ballymachugh); Wayne O'Hara (Granard/Ballymore), James Madden (Gowna), Kevin Shine (Mostrim); James McGivney (Northern Gaels), Conor Madden (Gowna, 0-1); Simon Cadam (Northern Gaels, 0-1), Robbie Smyth (Northern Gaels, 0-2), Dermot Reilly (Ballymachugh, 0-1); Benny Dempsey (Mostrim, 0-1), Johnny Murphy (Mostrim, 1-1), Cillian Lynn (Mostrim, 1-1).
Sub used: Michael Cullen (Mullahoran, 1-0) for D Reilly (51 mins).
GALLEN C.S: Eric Cornally; PJ Kidney, Ciaran Cahill, Niall Quinn; Shane Costello, John Egan, Conor Hanniffy; Conor Lowry, Callum Boland (0-5, three frees); Aaron McDonagh, Leon Fox, Blaine Rigney; Darragh Corbett (0-4), George Digan, Brian Grehan.
Subs used:- William Healy and Stephen Wren.
Referee: Martin Walsh (Offaly).