Hamilton was born out of wedlock in Charlestown, Nevis. He was orphaned as a child and taken in by a prosperous merchant. When he reached his teens, he was sent to New York to pursue his education. He took an early role in the militia as the American Revolutionary War began. As an artillery officer in the new Continental Army he saw action in the New York and New Jersey campaign. In 1777, he became a senior aide to Commander in Chief General George Washington, but returned to field command in time for a pivotal action securing victory at the Siege of Yorktown.