The name "Drumlion" is associated with the Táin Bó Cúailnge. As Queen Medbh assembled her forces for her invasion of Ulster a group of men coming to join her army from the province of Leinster camped on the highest ridge here. It was from this action that Drumlion received its Irish name, as Droim Laighean translates into the "Ridge of the men of Leinster".
Drumlion was known as a half-parish, following the amalgamation of Killukin & Killummod into the RC Parish of Croghan in 1858.
Séipéal Dhroim ar Chúil aka Drumercool Chapel was recorded by Lewis and on the OS Survey map of 1837. It had a thatch roof and was in a poor state of repair. Fundraising began for the building of a new house of worship on this site (in Drumercool townland).
In 1853, it was reported that the thatch roof on Drumercool chapel would "scarcely hold it together through this winter" and that on a wet Sunday the parishioners of Drumlion were forced to kneel on a wet floor, with the rain pouring down on their heads. Rev. Fr Matt Barrett RCC (Finner, Croghan) made a plea to the landlords of the district to subscribe to their building of a new church.
In the Freemans Journal August 08, 1854 (p.3) Rev Matthew J Barrett R.C.C. Croghan & Killukin reported on fundraising and that the erection of the new chapel in the parish was "now in progress".
Séipéal Dhroim Laighin aka Drumlion Chapel aka St. Michael's Church was completed by 1856. The church is still in use today and a number of key family names can be spotted on the stained-glass windows they sponsored. Drumlion Cemetery is one of the biggest in the district and still in active use today.
In 2006, Drumlion Sesquicentennial Committee published "St. Michael's Church - Drumlion - Co. Roscommon, 1856-2006: church, people, and landscape" by John Keenehan. (SBN 10: 0955382319 ISBN 13: 9780955382314 )
This book is chock-full of local history and a must-read for anyone researching the districts of Drumlion and Croghan.