Final answer:
The signing of the Declaration of Independence marked the official beginning of the war.
Step-by-step explanation:
The signing of the Declaration of Independence on July 4, 1776, marked the official beginning of the American Revolutionary War, turning the colonists' rebellion into a full-scale revolution.
The colonists' rebellion against Britain had become a full-scale revolution. In May 1775, the Second Continental Congress convened, following the confrontations at Lexington and Concord, Massachusetts, where the colonial militia had met British forces, and the infamous "shot heard around the world" was fired, leading to a retreat of the British army back to Boston.
As hostilities commenced, the Continental Congress met and soon established the Continental Army, selecting George Washington as its commander.
The growing tensions and hostilities culminated with Thomas Jefferson, using the ideas of John Locke, drafting the Declaration of Independence. This pivotal document, which was signed on July 4, 1776, detailed the colonists' grievances and declared American independence from Britain, moving protest and violence into an open state of war - the War for Independence had begun.