William sailed on his great expedition in the autumn with a fleet of
several hundred vesseles and a large number of transports. The Duke's
ship, with the consecrated banner at the masthead, led the fleet.
His army consisted of archers and cavalry. Its strength has been
variously estimated at from 14,000 men up to 60,000. They were partly
his own subjects, and partly hired soldiers, or those who joined for
the sake of plunder. William also carried a large force of smiths and
carpenters, with timber ready cut and fitted to set up a wooden
castle.