The Royal Munster Fusiliers held the 'home' Depot for their three Reserve Battalions at Ballymullen Barracks, Tralee, County Kerry, Ireland, where since 1881 most of the regiment's recruits enlisted in peacetime and received their first training before being assigned to regular battalions stationed around the UK and Ireland.
Their initial assignment was to be coastal defence, but due to losses reducing the 2nd (Regular) Battalion to less than 200 within a month of the war, most of the pre-war reservists, particularly those of the 3RMF, were used to rebuild it.
Both battalions who were popular during their stay, returned to Ireland by the end of 1915, 5th assigned to the Curragh, 4th to Fermoy, then to Bere Island in February 1916.
Reports of loss of rifles, Lewis guns and ammunition necessitated the massive transfer of the battalions out of the country in November, the 3rd to Devonport, England, the others to Scotland, 4th to Invergordon the 5th to Dreghorn.
[10] The garrison provided men for guard duty around the southern coast from the Shannon estuary round to Arklow, County Wicklow.
It was first stationed at Press Heath, Shropshire, then in January 1918 moved to Italy, based at Arquata Scrivia, providing guards for the British GHQ, airfield, ammunition stores and general lines of communication.
The unit received and provided drafts for many Irish regiments abroad resulting in a high fluctuation of personnel.