Rhode Island’s tradition of independence and dissent gave it a prominent role in the American Revolution. At approximately 2 a. m. on June 10, 1772, a band of Providence residents attacked the grounded revenue schooner Gaspee, burning it to the waterline for enforcing unpopular trade regulations within Narragansett Bay. Rhode Island was the first of the thirteen colonies to renounce its allegiance to the British Crown on May 4, 1776. It was also the last of the thirteen colonies to ratify the United States Constitution on May 29, 1790, and only under threat of heavy trade tariffs from the other former colonies and after assurances were made that a Bill of Rights would become part of the Constitution. During the Revolution, the British occupied Newport in December 1776. A combined Franco-American force fought to drive them off Aquidneck Island. Portsmouth was the site of the first African-American military unit, the 1st Rhode Island Regiment, to fight for the U. S. in the unsuccessful Battle of Rhode Island of August 29, 1778. A month earlier, the appearance of a French fleet off Newport caused the British to scuttle some of their own ships in an attempt to block the harbor. The British abandoned Newport in October 1779, concentrating their forces in New York City. An expedition of 5,500 French troops under Count Rochambeau arrived in Newport by sea on July 10, 1780. The celebrated march to Yorktown, Virginia in 1781 ended with the defeat of the British at the Siege of Yorktown and the Battle of the Chesapeake.