Complex sentence: Arthur's death thrust all his duties upon his younger brother, the 10-year-old Henry, who after a little debate succeeded him to the Dukedom of Cornwall in October 1502, and the Prince of Wales and Earl of Chester in February 1503.
Split into simpler sentences: Arthur's death thrust all his duties upon his younger brother, the 10-year-old Henry. After a little debate, Henry became the new Duke of Cornwall in October 1502, and the new Prince of Wales and Earl of Chester in February 1503.