Final answer:
John Marshall was convinced of the need for a strong national government during the Revolutionary War due to inadequate supplies sent to troops in 1777, shaping his later efforts as Chief Justice to bolster federal authority.
Step-by-step explanation:
John Marshall's experience during the Revolutionary War in 1777 convinced him about the need for a strong national government when the 13 states did not send adequate supplies to the freezing troops. The hardships faced by the Continental Army, especially during the winter at Valley Forge, highlighted the inefficiencies of the Articles of Confederation, leading to calls for a more centralized federal authority. Marshall's views were further shaped by his tenure as Chief Justice of the Supreme Court, where he worked to strengthen the authority of the federal government through landmark decisions.