=The Two Phases of the War.=—The war which opened with the battle of Lexington, on April 19, 1775, and closed with the surrender of Cornwallis at Yorktown on October 19, 1781, passed through two distinct phases—the first lasting until the treaty of alliance with France, in 1778, and the second until the end of the struggle. During the first phase, the war was confined mainly to the North. The outstanding features of the contest were the evacuation of Boston by the British, the expulsion of American forces from New York and their retreat through New Jersey, the battle of Trenton, the seizure of Philadelphia by the British (September, 1777), the invasion of New York by Burgoyne and his capture at Saratoga in October, 1777, and the encampment of American forces at Valley Forge for the terrible winter of 1777-78.
The final phase of the war, opening with the treaty of alliance with France on February 6, 1778, was confined mainly to the Middle states, the West, and the South. In the first sphere of action the chief events were the withdrawal of the British from Philadelphia, the battle of Monmouth, and the inclosure of the British in New York by deploying American forces from Morristown, New Jersey, up to West Point. In the West, George Rogers Clark, by his famous march into the Illinois country, secured Kaskaskia and Vincennes and laid a firm grip on the country between the Ohio and the Great Lakes. In the South, the second period opened with successes for the British. They captured Savannah, conquered Georgia, and restored the royal governor. In 1780 they seized Charleston, administered a crushing defeat to the American forces under Gates at Camden, and overran South Carolina, though meeting reverses at Cowpens and King’s Mountain. Then came the closing scenes. Cornwallis began the last of his operations. He pursued General Greene far into North Carolina, clashed with him at Guilford Court House, retired to the coast, took charge of British forces engaged in plundering Virginia, and fortified Yorktown, where he was penned up by the French fleet from the sea and the combined French and American forces on land.