At a midnight conference October 15, Cornwallis and his officers decided to send 350 of their bravest men on a surprise mission to disable some of the allied cannon in the second parallel batteries.  They chose as their point of attack the junction of the French and American sections of the trenches.  When challenged by sentries, they would pretend to be American reinforcements to the French and French reinforcements to the Americans.

The first part of the plan worked, as they rushed onto the redoubts, bayoneting the defenders but not pursuing them.  Their mission was to spike each cannon with their bayonet points.  While they were thus engaged, they were surprised by French grenadiers under Lafayette's brother-in-law, the Vicomte de Noailles, who had been aroused by the commotion.  A fierce bayonet fight continued until dawn.

By noon October 16, the Americans and French had cleared every one of the spiked cannons.  The renewed bombardment of Yorktown was even more vigorous than before.

The night of October 16, Cornwallis decided to escape from the siege by crossing the York River to Gloucester.  It would take three trips to get all of his men across.  The first contingent made it across to Gloucester, but it took two hours before the boats returned for the second group to embark.  Ten minutes after the boats had vanished into the night, rain began to fall.  It was soon a driving, pelting storm.  The boats were forced to return to the Yorktown shore.