The event that marked the beginning of the American Revolution was the outbreak of hostilities between British troops and colonial militia at the Battles of Lexington and Concord on April 19, 1775. These confrontations were the culmination of increasing tensions fueled by British taxation and colonial discontent. The phrase “the shot heard 'round the world” signifies the importance of this moment, as it ignited a full-scale war between the colonies and Britain. This conflict ultimately led to the Declaration of Independence in 1776 and the establishment of the United States.