Former American General Benedict Arnold (1741–1801)—now fighting for the British—easily took Richmond, Virginia, on January 5, 1781. George Washington (1732–1799), commander in chief of American forces, responded by sending soldiers to Virginia under the command of the Marquis de Lafayette of France (1757–1834). (The French officially joined the war on the side of the Americans in 1778.) By the spring of 1781, British General Charles Cornwallis (1738–1805) had reached Richmond. Washington and his ally, French commander Jean Baptiste Rochambeau (1725–1807), decided to join Lafayette and trap Cornwallis in Virginia.

While he was still in New York, Washington devised a scheme to conceal his plan of heading to Virginia—he wanted to keep the British from sending more troops there. Washington arranged to leak false information to confuse General Henry Clinton (1738–1795), the commander in chief of British forces in America; it was a complete...