The forces gathered by both sides at and about Yorktown were a heterogeneous mixture. The fleets were less so than the armies, but both contained fairly substantial numbers of men and officers from countries other than Britain and France: both, for instance, had Americans in their crews, and the French had numbers of volunteers from other European countries, notably Sweden. It was the armies, however, which were most startlingly mixed.

Cornwallis's force of about 8,500 men was composed mainly of two groups. Four thousand six hundred men were in the various units of the British army, mainly infantry, but with small groups of dragoons and artillerymen; the dragoons were attached to his headquarters. There were eight battalions of British foot regiments in the town, and elements of twelve others. That is not to say that all the men were from Britain, however. Some were certainly locally recruited into all these regiments in America, and the British army has never been particular about the origins of its soldiers, so some undoubtedly came from other European states; and the British recruits came from all parts of the British Isles. There were also two units from the ships, one of about 800 marines, and an unknown number of sailors from ships which had been scuttled or sunk in the bay, who were particularly useful as extra artillerists. Thus perhaps something in the area of sixty per cent of the whole army was British. The other large section was the Germans, over 2,000 of them, in several regiments recruited by their own princes and hired out to the British government; they were from Hesse and Ansbach-Bayreuth in the main. And nearly 800 men were American loyalists, in the two cavalry units of the Queen's Rangers and the British Legion, and the North Carolina Volunteers.

On the allies’ side, the American units of the Continental Army counted about 5,400 men, which included those brought from New York by Washington, those already in Virginia under La Fayette and Wayne, plus others who had turned up or rejoined at the prospect of a fight; and there were also over 3,000 of the Virginia Militia. The Continental units came from every state from New Hampshire to Virginia, but from none of the three southern states.