Among the principal operations proposed was an attack on the city of New York; and in accordance with these plans the allied forces of America and France moved against that city. Every necessary preparation had been made for the commencement of active operations, when, on August 14th, a letter reached General Washington in which the Count de Grasse informed him that the entire French West Indian fleet, with more than three thousand land forces, would shortly sail from Santo Domingo for the Chesapeake, intimating, however, that he could not remain longer than the middle of October, at which time it would be necessary for him to be on his station again. As the limited period which the Count could spend in the service of the allies was not sufficient to warrant the supposition that he could be useful before New York, the entire plan of the campaign was changed; and it was resolved to proceed to Virginia, with the whole of the French troops and as many of the Americans as could be spared from the defence of the posts on the Hudson; and instead of besieging Sir Henry Clinton, in his head-quarters in New York, a movement against Lord Cornwallis and the powerful detachment under his command was resolved on. At the period in question Lord Cornwallis had moved out of the Carolinas, formed a junction with the force under General Phillips, and had overrun the lower counties of Virginia, until General Lafayette, who had been sent to the State some weeks after, by superior skill and the most active exertions had succeeded in checking his progress. The purpose of the allies was to prevent the escape of Lord Cornwallis from his position near Yorktown; and General Lafayette was ordered to make such a disposition of his army as should be best calculated to effect that purpose. In case this purpose should be defeated, and Lord Cornwallis succeed in effecting a retreat into North Carolina, it was designed to pursue him with sufficient force to overawe him: while the remainder of the armies, at the same time, should proceed, with the French fleet, to Charleston, which was, at the same time, the enemy's head-quarters in the South. The marine force of the allies was composed of two fleets--that of Admiral Count de Grasse, then on its way from the West Indies, composed of twenty-six sail of the line and several frigates; and that of Admiral Count de Barras, then at anchor in Newport, composed of eight sail of the line, besides transports and victuallers: their military force embraced the main bodies of the American and French armies, under Generals Washington and Rochambeau, then near New York; the detachment of American troops, under General Lafayette, then in Virginia; and more than three thousand French troops, under General Saint-Simon, who were then on their way from the West Indies with the Count de Grasse.