Complex sentence: O’Neill and O’Donnell, and their families left Ireland on that historic day--14th of September 1607-in the Flight of the Earls and their lands in Ulster were confiscated and colonized in the Plantation of Ulster.
Split into simpler sentences: O’Neill and O’Donnell, and their families left Ireland on that historic day--14th of September 1607-in the Flight of the Earls. Their lands in Ulster were confiscated and colonized in the Plantation of Ulster.