Complex sentence: In the following days, Fitzthomas, followed reluctantly by Donal MacCarthy, laid waste to Lord Barry's territory of Ibawne, since he refused to join the rebellion; from his base at Kinsale, Florence closed all the approaches into his own country.
Split into simpler sentences: In the following days, Fitzthomas, followed reluctantly by Donal MacCarthy, laid waste to Lord Barry's territory of Ibawne, on the ground that Barry had refused to join the rebellion. From his base at Kinsale, Florence closed all the approaches into his own country.