In February 1776, colonists received news that Parliament passed the Prohibitory Act, which established a blockade of American ports and declared American ships to be enemy vessels. Although the measure amounted to a virtual declaration of war by the British, Congress did not have immediate authority to declare independence until each individual colony authorized its delegates to vote for independence. On June 11, Congress appointed the "Committee of Five," consisting of John Adams of Massachusetts, Benjamin Franklin of Pennsylvania, Thomas Jefferson of Virginia, Robert R. Livingston of New York, and Roger Sherman of Connecticut, to draft an official declaration of independence. Congress unanimously adopted its final version of the Declaration on July 4, marking the formation of the United States of America. Historians believe that the Old State House Bell, now known as the Liberty Bell, was one of the bells rung to mark the reading of the Declaration on July 8.