Complex sentence: On 4 September 1922, Anti-Treaty IRA unit under Liam Pilkington took the Dromhaire barracks, in County Sligo, because the Free State garrison in the Dromhaire barracks surrendered.
Split into simpler sentences: On 4 September 1922, Anti-Treaty IRA unit under Liam Pilkington takes Dromhaire barracks, in county Sligo. The Free State garrison in the Dromhaire barracks surrendered.