Final answer:
The second phase of the Battle of Hastings is best characterized by William changing his battle strategy, using the mobility of his cavalry to disrupt enemy defenses, as depicted on the Bayeux Tapestry.
Step-by-step explanation:
The second phase of the Battle of Hastings was marked by a significant change in tactics by William, the Duke of Normandy. As depicted in the Bayeux Tapestry, William's innovative and flexible use of cavalry was a defining element of the Normans’ approach to warfare. The Norman cavalry were able to swiftly charge and retreat, which disrupted the English defenses and created openings for the Norman infantry to advance. This maneuverability of the mounted troops, coupled with their protective gear such as conical steel helmets, mail shirts, and use of shields and spears, was a critical component of Norman military strategy. Therefore, the correct answer to the question is C. William changed his battle strategy.