At meeting at Wethersfield, Connecticut, in May 1781, George Washington met with Lieutenant General Comte de Rochambeau, the commander of French land forces in North America. The French reluctantly agreed to bring their West Indian fleet into the war on behalf of the Americans, but did not commit to where the ships would be deployed. Washington wanted this force to be used in a coordinated attack on Henry Clinton’s army in the New York City area. The need for French cooperation was obvious — Washington’s army in the Hudson Highlands north of Manhattan numbered only about 3,500 men, while Clinton’s force was more than 14,000.
The crucial decision about where the French Navy would participate was left to the West Indian commander, François Joseph Paul, Comte de Grasse. Two options existed: New York and Virginia.
Washington feared that committing his army to a campaign in the South was an invitation to disaster. Lord Charles Cornwallis, the British commander in the area, needed only to move his troops into the interior of the Carolinas, live off the land and wait for assistance from New York. Clinton could sail an army to Virginia much more rapidly than Washington could by a forced march.
On July 5, French land forces arrived in the Hudson Valley from their earlier base in Rhode Island. Lengthy preparations began for a combined attack on New York. However, in mid-August Washington received a letter from Admiral de Grasse indicating that the French fleet would be available for service in Chesapeake Bay by the end of the month and would remain there until October 15. The time limit for the fleet’s participation was imposed by the high point of hurricane season in the Indies.
On August 20, American and French forces began moving south on their journey of more than 450 miles. Great efforts were made to make it appear that the combined armies were headed toward a direct confrontation against Clinton in New York coastal areas. If the true intentions were discovered, Clinton could send reinforcements by sea to Cornwallis in Virginia.
Washington left a small force behind under the command of William Heath and the bulk of the Franco-American force moved west and south. They marched through New Jersey, covering 15 miles a day in good weather. It was not until September 1 and 2, when the army reached Philadelphia, that Clinton realized what had happened. The British command was disturbed, but not panicky; they were convinced that the strength of the British fleet would prevent matters in the southern theater from getting out of hand.
Washington faced another kind of crisis in Philadelphia. Troops had not been paid and no funds were available. A mutiny was averted when Robert Morris, the prime procurer of munitions and money during the war, secured the needed funds from Rochambeau.
The armies proceeded to Head of Elk in Maryland and arrived in Baltimore on September 12. Three days later, Washington and Rochambeau met with the leader of American forces in the South, the Marquis de Lafayette. On the 17th, Washington and Rochambeau boarded the Ville de Paris and plotted strategy with Admiral de Grasse, who had arrived in the Chesapeake as promised. It was decided that de Grasse would seal off the mouth of the bay to deny entry to the anticipated British fleet. Meanwhile, the land forces would take up positions surrounding Cornwallis in Yorktown. Trenches would be constructed and artillery set in place.
On September 28, American and French forces left Williamsburg and marched to the areas surrounding Yorktown, where they initiated a siege of British fortifications.
See Yorktown Campaign and Timeline of the War of Independence.