In 1780, as America struggled, Thomas Paine wrote:
Tyranny, like hell, is not easily conquered; yet we have this consolation with us, that the harder the conflict, the more glorious the triumph.
After the patriots' victory at Cowpens (January 17, 1781), the momentum of war turned against the British. Generals
Nathanael Greene and Daniel Morgan employed unusual but brilliant strategy to stop the British as they retreated north. Men like Andrew Pickens and Francis Marion continued to frustrate the British.
Redcoat victories were few and casualties high. The battle of Guilford Courthouse, a technical British victory, left Lord Charles Cornwallis in a weakened position. Things had drastically changed for Cornwallis since the early days of his campaign in the colonies. Many battles (follow this link to an interactive map) had been fought and won by the British, but Lord General Cornwallis would soon be known in London as "the man who lost America."
By the time Cornwallis and his men reached Yorktown, America was taking full advantage of France's offer to help. French assistance on land and sea was key to the ultimate American victory. (Ironically, Louis XVI's decision to aid America ultimately cost him his head since a declining French economy - caused, in part, by the American war - led to the French Revolution and, for Louis, the guillotine.)