Complex sentence: In response, Catholics formed a group known as the Defenders and regularly clashed with the Peep O'Day Boys until violence reached a pitch in 1795, when the two groups fought the "battle of the Diamond" in Loughall, county Armagh.
Split into simpler sentences: In response, Catholics formed a group known as the Defenders. Violence reached a pitch in 1795, when the two groups fought the "battle of the Diamond" in Loughall, county Armagh.