French ships were blocking the bay, so
that Cornwallis and the British there couldn't get supplies. Also the
British couldn't escape from the bay. And, Washington and
his army where coming from land. *I think there were French
troops of the ground as well...* So Cornwallis couldn't escape from
any direction. Cornwallis was outnumbered as well-->19,300
soldiers (10,800 French 8,500 Americans) 24 French wars ships, and
375 guns to 7,500 British soldiers and 240 guns The odds were against
him, he had to surrender for the sake of his men. There are lots more
reasons... like he was going to get help but it never came.