Complex sentence: Cochwillan was built around 1465 by William ap Gruffudd who for supporting Henry Tudor at the Battle of Bosworth was rewarded by being named Sheriff of Caernarvonshire.
Split into simpler sentences: Cochwillan was built around 1465 by William ap Gruffudd who supported Henry Tudor at the Battle of Bosworth. He was rewarded by being named Sheriff of Caernarvonshire.