Complex sentence: With his new supporters, Dermot reclaimed Leinster but died shortly afterwards in 1171; de Clare then claimed Leinster for himself, but the situation in Ireland was tense and the Anglo-Normans heavily outnumbered.
Split into simpler sentences: With his new supporters, Mac Murchada reclaimed Leinster but died shortly afterwards in 1171; de Clare then claimed Leinster for himself. The situation in Ireland was tense and the Anglo-Normans heavily outnumbered.