Where was 'Knocknagow'?

From the James Maher edited Romantic Slievenamon

Writing in Tipperary's Annual for 1911 (page 105), Richard M.O'Hanrahan, of Fethard, states :

An erroneous idea prevails amongst a section of Tipperary men regarding the location of 'Knocknagow'. It has been stated that Mocklershill, mid-way between Cashel and Fethard is 'Knocknagow'. Such is not the case, as 'Knocknagow', as Kickham wished it to be understood, embraced the parishes of Mullinahone, Grangemockler, Drangan and Cloneen, though some of the characters, such as Fr.McMahon (who was in reality Dean MacDonnell of Cashel) were drawn from other places, notably Fethard, Cashel and Killenaule districts. Charles J.Kickham gave the title 'Knocknagow' to the book for the simple reason that 'Crickeenagow' (the smith's little hill) was his mother's native place, and I have it on reliable authority that it was at Crickeennagow—and not Mullinahone—that Kickham was born. At the same time Mullinahone can claim Kickham as her own, as his home was there from his infancy, and the best part of his boyhood and manhood days were spent in the historic little town that nestles beside the Anner, at the foot of Slievenamon.