Final answer:
Marquis de Lafayette was the trusted French aide to George Washington during the American Revolutionary War, contributing to the American victory by securing French support.
Step-by-step explanation:
The French nobleman who became Washington's trusted aide was Marquis de Lafayette. Lafayette played a vital role during the American Revolutionary War. He was a young French aristocrat who volunteered to fight in the conflict and quickly became a confidant and trusted military officer to General George Washington, the leader of the Continental Army.
Lafayette's contribution was significant in securing French support for the American cause, which was crucial for the American victory. Despite the turmoil during the French Revolution, where figures like Robespierre and Napoleon Bonaparte rose and fell, Lafayette's dedication to the ideals of liberty and his support for the American Revolution cemented his legacy in both American and French history.