The allied American and French armies joined Lafayette at Williamsburg, Virginia, September 25, 1781, and on the 27th there was a besieging army there of sixteen thousand men, under the chief command of Washington, assisted by Rochambeau. The British force, about half as numerous, were mostly behind intrenchments at Yorktown. On the arrival of Washington and Rochambeau at Williamsburg, they proceeded to the _Ville de Paris_, De Grasse’s flag-ship, to congratulate the admiral on his victory over the British admiral Graves on the 5th, which had prevented British relief of Yorktown by sea, and to make specific arrangements for the future. Preparations for the siege were immediately begun. The allied armies marched from Williamsburg (September 28th), driving in the British outposts as they approached Yorktown, and taking possession of abandoned works. The allies formed a semicircular line about two miles from the British intrenchments, each wing resting on the York River, and on the 30th the place was completely invested. The British at Gloucester, opposite, were imprisoned by French dragoons under the Duke de Lauzun, Virginia militia, led by General Weedon, and eight hundred French marines. Only once did the imprisoned troops attempt to escape from that point. Tarleton’s legion sallied out, but were soon driven back by De Lauzun’s cavalry, who made Tarleton’s horse a prisoner and came near capturing his owner. [Illustration: SIEGE OF YORKTOWN] In the besieging lines before Yorktown the French troops occupied the left, the West India troops of St. Simon being on the extreme flank. The Americans were on the right; and the French artillery, with the quarters of the two commanders, occupied the centre. The American artillery, commanded by General Knox, was with the right. The fleet of De Grasse was in Lynn Haven Bay to beat off any vessels that might attempt to relieve Cornwallis. On the night of October 6th heavy ordnance was brought up from the French ships, and trenches were begun at six hundred yards from the British works. The first parallel was completed before the morning of the 7th, under the direction of General Lincoln; and on the afternoon of the 9th several batteries and redoubts were finished, and a general discharge of heavy guns was opened by the Americans on the right. Early on the morning of the 10th the French opened several batteries on the left. That evening the same troops hurled red-hot balls upon British vessels in the river, which caused the destruction by fire of several of them--one a forty-four-gun ship.