April 8, 1780 – The British attack begins against Charleston as warships sail past the cannons of Fort Moultrie and enter Charleston harbor. Washington sends reinforcements.
May 6, 1780 – The British capture Fort Moultrie at Charleston, South Carolina.
May 12, 1780 – The worst American defeat of the Revolutionary War occurs as the British capture Charleston and its 5400-man garrison (the entire southern American Army) along with four ships and a military arsenal. British losses are only 225.
May 25, 1780 – After a severe winter, Gen. Washington faces a serious threat of mutiny at his winter camp in Morristown, New Jersey. Two Continental regiments conduct an armed march through the camp and demand immediate payment of salary (overdue by 5 months) and full rations. Troops from Pennsylvania put down the rebellion. Two leaders of the protest are then hanged.
June 11, 1780 – A new Massachusetts constitution is endorsed asserting "all men are born free and equal," which includes black slaves.
June 13, 1780 – Gen. Horatio Gates is commissioned by Congress to command the Southern Army.
June 23, 1780 – American forces defeat the British in the Battle of Springfield, New Jersey.
July 11, 1780 – 6000 French soldiers under Count de Rochambeau arrive at Newport, Rhode Island. They will remain there for nearly a year, blockaded by the British fleet.
August 3, 1780 – Benedict Arnold is appointed commander of West Point. Unknown to the Americans, he has been secretly collaborating with British Gen. Clinton since May of 1779 by supplying information on Gen. Washington's tactics.
August 16, 1780 – A big defeat for the Americans in South Carolina as forces under Gen. Gates are defeated by troops of Gen. Charles Cornwallis, resulting in 900 Americans killed and 1000 captured.
August 18, 1780 – An American defeat at Fishing Creek, South Carolina, opens a route for Gen Cornwallis to invade North Carolina.
September 23, 1780 – A British major in civilian clothing is captured near Tarrytown, New York. He is found to be carrying plans indicating Benedict Arnold intends to turn traitor and surrender West Point. Two days later, Arnold hears of the spy's capture and flees West Point to the British ship Vulture on the Hudson. He is later named a brigadier general in the British Army and will fight the Americans.
October 7, 1780 – Gen. Cornwallis abandons his invasion of North Carolina after Americans capture his reinforcements, a Loyalist force of 1000 men.
October 14, 1780 – Gen. Nathanael Greene, Washington's most able and trusted General, is named as the new commander of the Southern Army, replacing Gen. Gates. Greene then begins a strategy of rallying popular support and wearing down the British by leading Gen. Cornwallis on a six month chase through the back woods of South Carolina into North Carolina into Virginia then back into North Carolina. The British, low on supplies, are forced to steal from any Americans they encounter, thus enraging them.
