Complex sentence: Thornbury, quicker off the mark than his rival, set out for Avignon to secure Papal confirmation of his election; the ship sank in a storm with the loss of all lives on board: the dead were said to number more than 150.
Split into simpler sentences: Thornbury, quicker off the mark than his rival, set out for Avignon to secure Papal confirmation of his election. The ship sank in a storm with the loss of all lives on board: the dead were said to number more than 150.