The most accurate response regarding George Washington's contribution to the American Revolution is:
He led American soldiers in Valley Forge.
George Washington played a crucial role as the commander of the Continental Army, particularly during the harsh winter at Valley Forge in 1777-1778, where he maintained the morale and resolve of his troops despite difficult conditions.
While he did negotiate agreements with some Native American groups and recognized the potential of allowing enslaved people to serve in the army, he did not immediately free them or lead the Continental Congress. His primary and significant role was as a military leader during the war.