With the French now involved, the British stepped up their efforts in the southern colonies since they felt that most Southerners were Loyalists. A campaign began in late 1778, with the capture of Savannah, Georgia. Shortly thereafter, British troops drove toward Charleston, South Carolina, the principal Southern port. The British also brought naval and amphibious forces into play there, and they managed to bottle up American forces on the Charleston peninsula. On May 12 General Benjamin Lincoln surrendered the city and its 5,000 troops, the greatest American defeat of the war.