Looking back a century, to 1921, our country was coming to the end of the Anglo Irish war and heading into Civil War. To get a feel for the comings and goings of the time around Clonmethan and Fingal, the testimony of John Gaynor from the military archives is a nice read. Gaynor was a Captain in the Balbriggan Company of the Irish Volunteers.
The map below highlights the locations described. More can be found here.