Fort Washington, a small redoubt or earth, is not far from the Arch and has been carefully preserved against the encroachments of Time. The lines of the earthworks may also be made out. A historic site is Yorktown, Virginia, the sleepy little village on the peninsula between the James and York rivers Cornwallis surrendered to Washington and the French allies in 1781, thus making sure of American Independence, and where the Army of the Potomac encamped under McClellan in 1862, throwing up massive earthworks. The traces of both Cornwallis’ and McClellan’s encampments are easily to be made out to-day. [Illustration: National Memorial Arch Washington’s Headquarters SCENES AT VALLEY FORGE] The American and French forces marched from Williamsburg, September 28, 1781, driving in the British outposts at Yorktown as they approached and taking possession of the abandoned outworks. Forming a semicircular line about two miles from the British intrenchments they completely invested the enemy, the York River enclosing his forces to the northeast. October 17, Cornwallis offered to discuss terms of surrender. The beginning of the year 1863--to make a jump from the Revolution to the Civil War--saw the turning of the tide for the United States, and it was in this year that the decisive battles of Vicksburg, Gettysburg and Chattanooga were fought. The battle-grounds of each of these engagements have been created national parks and are maintained in such a fashion that the visitor may follow the movements of the troops in those great clashes. After the capture of the posts north of Vicksburg, on the Mississippi, and the opening of the mouth of the river by Farragut’s taking of New Orleans in 1862, Vicksburg was the only remaining defence of the Confederacy on the Mississippi, and the sole remaining link between the Confederacy’s east and west portions. The principal works of the city were on a commanding eminence, giving a clear sweep of the river and the surrounding country, which was swampy and almost impassable. They were competently manned, capably officered and well supplied. The place, altogether, was deemed almost impregnable. To follow out all of the steps by which its reduction was brought about is not the province of this chapter. The United States troops under the comparatively unknown commander, U. S. Grant, began to operate at the end of January, 1863, and on July 4 concluded their task in the unconditional surrender of the main fortification of the Confederates. The surrender of Vicksburg came one day after the conclusion of the battle of Gettysburg which occupied the first three days of July. The reservation of the Vicksburg National Park contains 1,255.07 acres and was acquired pursuant to an Act of Congress approved February 21, 1899.