While the close investment of the British army was delayed, only until the troops from the north should arrive, serious apprehensions were excited that the brilliant results confidently anticipated from the superiority of the land and naval forces of the allies, would be put in imminent hazard.

Information was received that a reinforcement of six ships of the line under Admiral Digby had reached New York.  Confident that the British fleet, thus augmented, would attempt every thing for the relief of Lord Cornwallis, De Grasse expected to be attacked by a force not much inferior to his own.  Thinking his station within the Chesapeake unfavourable for a naval combat, he designed to change it, and communicated to General Washington his intention to leave a few frigates to block up the mouths of James and York Rivers, and to put to sea with his fleet in quest of the British.  If they should not have left the harbour of New York, he purposed to block them up in that place; supposing that his operations in that quarter would be of more service to the common cause, than his remaining in the bay, an idle spectator of the siege of York.

The Commander-in-chief was much alarmed at this communication.  Should the admiral put to sea, the winds and many accidents might prevent his return to the Chesapeake.  During his absence, a temporary naval superiority might be acquired by the British in those waters, and the army of Lord Cornwallis might be placed in perfect security.  The movement would expose to the caprice of fortune, an object of vast importance, which was now reduced almost to certainty.  The admiral was therefore entreated to preserve his station.

Fortunately, the wishes of the general prevailed, and the admiral consented to relinquish those plans of active enterprise which his thirst for military glory had suggested, and to maintain a station which the American general deemed so conducive to the interests of the allies.

[Sidenote:  September 25.]

On the 25th of September, the last division of the allied troops arrived in James River, and were disembarked at the landing near Williamsburg; soon after which, the preparations for the siege were completed.

[Sidenote:  Yorktown invested.]

York is a small village on the south side of the river which bears that name, where the long peninsula between the York and the James, is only eight miles wide.  In this broad and bold river, a ship of the line may ride in safety.  Its southern banks are high, and, on the opposite shore, is Gloucester Point, a piece of land projecting deep into the river, and narrowing it, at that place, to the space of one mile.  Both these posts were occupied by Lord Cornwallis.  The communication between them was commanded by his batteries, and by some ships of war which lay under his guns.

The main body of his army was encamped on the open grounds about Yorktown, within a range of outer redoubts and field works, calculated to command the peninsula, and impede the approach of the assailants; and Lieutenant Colonel Dundass, with a small detachment consisting of six or seven hundred men, held the post at Gloucester Point.  He was afterwards reinforced by Lieutenant Colonel Tarlton.