Excerpts from Books and Wikipedia
"British attempts to disarm the Massachusetts militia in Concord led to open combat and a British defeat on April 19, 1775. Militia forces then besieged Boston, forcing a British evacuation in March 1776, and Congress appointed George Washington to command the Continental Army. Concurrently, the Americans failed decisively in an attempt to invade Quebec and raise insurrection against the British. On July 2, 1776, the Second Continental Congress voted for independence, issuing its declaration on July 4. Sir William Howe launched a British counter-offensive, capturing New York City and leaving American morale at a low ebb. However, victories at Trenton and Princeton restored American confidence. In 1777, the British launched an invasion from Quebec under John Burgoyne, intending to isolate the New England Colonies. . . . Burgoyne's defeat had drastic consequences. France formally allied with the Americans and entered the war in 1778." Cornwallis mounted a "Southern strategy" dependent upon a Loyalist uprising, but too few arose. Cornwallis retreated to Yorktown intending an evacuation, but was blocked by the French navy. [Wikipedia]