Complex sentence: The rebel leader then encouraged a rebellion by the White Knight in the southern province of Munster, while O'Donnell moved into the western province of Connacht, with the expectation O'Neill would push southward to join with the White Knight.
Split into simpler sentences: The rebel leader encouraged a rebellion by the White Knight in the southern province of Munster. And then O'Donnell moved into the western province of Connacht, with the expectation O'Neill would follow in a push southward to join with the White Knight.