Cornwallis, seeing the formidable combination which the French and Americans were making to crush him, sent message after message to New York to ask for aid from the commander-in-chief, and received assurances from him that he would at once sail with 4000 troops to join him. Accordingly, in obedience to his orders, Lord Cornwallis fortified himself at Yorktown.

On September 28 the combined army of French and Americans, consisting of 7000 of the former and 12,000 of the latter, appeared before Yorktown and the post at Gloucester. Lord Cornwallis had 5960 men, but so great had been the effects of the deadly climate in the autumn months that only 4017 men were reported as fit for duty.

The enemy at once invested the town and opened their trenches against it. From their fleet they had drawn an abundance of heavy artillery, and on October 9 their batteries opened a tremendous fire upon the works. Each day they pushed their trenches closer, and the British force was too weak, in comparison with the number of its assailants, to venture upon sorties. The fire from the works was completely overpowered by that of the enemy, and the ammunition was nearly exhausted. Day after day passed and still the promised re-enforcements did not arrive. Lord Cornwallis was told positively that the fleet would set sail on October 8, but it came not, nor did it leave port until the 19th, the day on which Lord Cornwallis surrendered.