The American Revolution: A History by Gordon S. Wood Page A

INDEPENDENCE
    However important constitution-making of the states and the Union may have been to the Revolutionaries, it would mean nothing if independence were not achieved. Once Britain had determined to enforce its authority with troops, Americans knew that they had to take up arms to support their beliefs and their hopes for the future. For over a year before the Declaration of Independence, American and British forces had been at war. It was a war that would go on for nearly eight years—the longest conflict in American history until the Vietnam War two centuries later.
    The war for independence passed through a series of distinct phases, growing and widening until what had begun in British eyes as a breakdown in governmental authority in a section of the empire became a worldwide struggle. For the first time in the eighteenth century, Great Britain found itself diplomatically isolated; at one point in 1779 it was even threatened with French invasion. The war for American independence thus eventually became an important episode in Britain’s long struggle with France for global supremacy, a struggle that went back a century and would continue for another generation into the nineteenth century.
    British troops had suffered heavy losses in their first clashes with the American militia in Massachusetts in the spring of 1775—at Lexington and Concord and especially in the bloody battle of Bunker Hill. This initial experience convinced the British government that it was not simply dealing with a New England mob, and it swept away almost every objection the members of the ministry had to a conquest of the colonies. During the summer of 1775 the Second Continental Congress appointed fourteen generals, authorized the invasion of Canada, and organized a Continental field army under George Washington. Aware that the southern colonies were suspicious of Massachusetts’s fanaticism, John Adams pushed for the selection of the forty-three-year-old Virginia militia colonel as commander in chief. It was an inspired choice. Washington, who attended the Congress in uniform, looked the part: he was tall and composed, with a dignified soldierlike air that inspired confidence. He was, as one congressman said, “no harum-scarum, ranting, swearing fellow, but sober, steady, and calm.”
    All these congressional actions only confirmed the British government’s realization that it was now involved in a military rather than a police action. This new understanding of what Britain was up against dictated a conventional eighteenth-century military policy of maneuver and battle between organized armies.
    This change of strategy required that the British evacuate Boston and transfer their main forces to New York, with its presumably more sympathetic population, its superior port, and its central position. Accordingly, in the summer of 1776, Sir William Howe, who replaced Gage as commander in chief of the British army in North America, sailed into New York Harbor with a force of more than 30,000 men. Howe aimed to cut New England off from the other rebels and to defeat Washington’s army in a decisive battle. He was to spend the next two frustrating years trying to realize this plan.
    On the face of it, a military struggle seemed to promise all the advantage to Great Britain. Britain was the most powerful nation in the world, with a population of about 11 million, compared with only 2.5 million colonists, a fifth of whom were black slaves. The British navy was the largest in the world, with nearly half its ships initially committed to the American struggle. The British army was a well-trained professional force, numbering at one point in 1778 nearly 50,000 troops stationed in North America alone; and more than 30,000 hired German mercenaries were added to this force during the war.
    To confront this military might the Americans had to start from scratch. The Continental Army they created numbered usually less than 5,000 troops, supplemented by