Complex sentence: O'Rourke and forces loyal to him were holed up in their keeps as the countryside of West Breifne was ravaged by attacks and on April 25 1603 Mountjoy reported that Brian Óg had been toppled, forced into the forests like "a wood kerne".
Split into simpler sentences: O'Rourke and forces loyal to him were holed up in their keeps as the countryside of West Breifne was ravaged by attacks. On April 25 1603 Mountjoy reported that Brian Óg had been toppled, forced into the forests like "a wood kerne".