Complex sentence: Many of the R.I.C. Barracks attacked were abandoned by the R.I.C., who though an armed force, were unable to defend them-they were then stationed in the larger towns where they could more easily defend themselves by virtue of their larger numbers.
Split into simpler sentences: Many of the R.I.C. Barracks attacked were abandoned by the R.I.C., who though an armed force, were unable to defend them. They were then stationed in the larger towns where they could more easily defend themselves by virtue of their larger numbers.