Making the capture of Charlestown their chief priority, the British sent Sir Henry Clinton, who laid siege to Charleston on April 1, 1780, with about 14,000 troops and 90 ships. Bombardment began on March 11, 1780. The Patriots, led by Benjamin Lincoln, had about 5,500 men and inadequate fortifications to repel the forces against them. After the British cut his supply lines and lines of retreat at the battles of Monck's Corner and Lenud's Ferry, Lincoln's surrender on May 12, 1780 became the greatest American defeat of the war.