Complex sentence: The 13th Earl's son, Thomas Courtenay, 14th Earl of Devon, fought on the losing Lancastrian side at the Battle of Towton, and was captured and beheaded, and all his honours forfeited by attainder.
Split into simpler sentences: The 13th Earl's son, Thomas Courtenay, 14th Earl of Devon, fought on the losing Lancastrian side at the Battle of Towton. He was captured and beheaded, and all his honours forfeited by attainder.