Lincoln rejoined Washington outside New York in August 1778, and was appointed commander of the Southern department in September. Washington sent Lincoln, Lafayette and Lee (Henry "Light Horse Harry") to the Southern Department to oppose the British army under Clinton and Cornwallis. Lincoln participated in the unsuccessful French-led siege of Savannah, Georgia in October 1779, after which he retreated to Charleston, South Carolina. He took command of the garrison of Charleston. In March 1780 the city was surrounded by a sizable British force dispatched from New York. After a relatively brief siege Lincoln was forced to surrender more than 5,000 men to Lieutenant General Sir Henry Clinton on May 12, 1780, but did so in a way that allowed the South Carolina militia to escape as well as some Continental forces, that annoyed the British toward Lincoln.