This brigade in the unit formation listed here was not formed by the first critical date 11 July 1921 and all data is for the period 1 July 1922 only. The strength of the Brigade on 1 July 1922 was 664 all ranks. The data for the brigade in the form in which it existed on 11 July 1921 is given in the following files. The 1 Battalion was then designated the 2 Battalion, North Galway Brigade, 1 Western Division. The 2 Battalion was then designated the 1 Battalion, South Roscommon Brigade, 1 Western Division and the 3 Battalion was then designated the 2 Battalion, South Roscommon Brigade, 1 Western Division. This data is given in sequence for that Division.

1 (Glenamaddy) Battalion: Unit strength on 1 July 1922 was 302 all ranks. The companies of the 1 Battalion were located as follows: Dunmore, Kiltevna, Williamstown, Kilcroan, Glynsk, Kilbegnet, Kilkerrin, Clonberne, Glenamaddy and Poleredmond.
2 (Castlerea) Battalion: Unit strength on 1 July 1922 was 224 all ranks. The companies of the 2 Battalion were located as follows: Loughlynn, Ballingare, Moore, Cloonbonniffee, Treen, Cloonfad, Ballinlough, Frenchpark, Granlaghan, Gortaganny, Lisliddy and Castlerea.
3 (Oran) Battalion: Unit strength on 1 July 1922 was 128 all ranks. The companies of the 3 Battalion were located as follows: Cloverhill, Ballinaheglish, Castleplunket, Fuerty, Donamon and Ballintubber.

Active Service Unit: sources state that the Castlerea Brigade, Active Service Unit, was part of the 3 (Oran) Battalion and on 1 July 1922 it had a strength of 27 all ranks. These personnel were drawn from the battalions of the brigade.