The action of Graves spelled the doom of Cornwallis.

The most potent fleet ever gathered in those waters cut him off from rescue by sea.
Yorktown fronted on the York River with a deep ravine and swamps at the back of the town.

From the land it could on the west side be approached by a road leading over marshes and easily defended, and on the east side by solid ground about half a mile wide now protected by redoubts and entrenchments with an outer and an inner parallel.

Could Cornwallis hold out?
At New York, no longer in any danger, there was still a keen desire to rescue him.

By the end of September he received word from Clinton that reinforcements had arrived from England and that, with a fleet of twenty-six ships of the line carrying five thousand troops, he hoped to sail on the 5th of October to the rescue of Yorktown.