Complex sentence: The town grew up around a castle established there by Manghus Ó Domhnaill, ruler of Tír Chonaill (mostly modern County Donegal), in the 16th century, and later became a British Army garrison town until most of Ireland won independence as a dominion in 1922.
Split into simpler sentences: The town grew up around a castle built there by Manghus Ó Domhnaill, ruler of Tír Chonaill (mostly modern County Donegal), in the 16th century. It later became a British Army garrison town until most of Ireland won independence as a dominion in 1922.