Complex sentence: Only when Silken Thomas, the 10th Earl of Kildare, rebelled against Henry VIII did they fall from power; even then, they regained some of their influence under the later Tudors.
Split into simpler sentences: Only when Silken Thomas, the 10th Earl of Kildare, rebelled against Henry VIII did they fall from power. Even then, they regained some of their influence under the later Tudors.