After the disaster at Saratoga the British decided to implement the next part of their strategy, to cut the Southern colonies off from the rest. If they could take Georgia, South Carolina, North Carolina and part of Virginia out of the war, they still might be able to win.
The British believed they would find a great many loyalists in the south who would help them in their quest to destroy the colonial patriots.
The British started their attempt to conquer the Southern Colonies by sending one of their best generals with an army of about 2,000 men to attack Charleston, South Carolina. At the 1st Battle of Charleston, they were soundly beaten. They departed back to New York to return later.
In 1779, the British came back. This time they landed and captured the port of Savannah Georgia, the southernmost of the colonies.
Once in Savannah, the British quickly captured all of Georgia. The British General Clinton then moved into South Carolina. He surrounded the colonial army in Charleston and started a siege.
The British navy set up a blockage, which stopped all colonial ships from entering Charleston. The colonials soon ran out of food and ammunition. About 8,000 colonial soldiers and militia surrendered, which was nearly the entire southern colonial army.
Clinton then proceeded inland and captured most of South Carolina. The British built a line of forts to protect what they had captured. With these forts in place to protect his rear areas, General Clinton turned his army over to General Cornwallis and returned to New York. It looked like the British strategy might work.
Cornwallis moved into North Carolina. This is where things started to go wrong for the British. They seemed to win all the battles, yet couldn't quite seem to ever really beat the colonists.
Think back to colonial advantages during the revolution.
Cornwallis could not get reinforcements quickly.
The colonists were defending their own towns and farms. Wherever Cornwallis went there was a whole new bunch of Militia waiting for him.
The British did something really bad. They refused a request for Quarter. The definition of "Quarter" in war means mercy, please do not kill us, but show us mercy.
When a group of Colonial Militia was fighting a detachment of British soldiers under the command of Major Tarleton, they were being defeated and asked for Quarter. He refused and his troops massacred the colonists. This gave the colonists a rallying call. It also gave them a very good reason not to surrender.
What would you do if you might get shot if you tried to surrender? The colonists were not about to risk asking again for Quarter. They fought that much harder instead. Finally General Washington sent some of the Continental Army down south under the command of one of his best generals, Nathaniel Greene.
The British were defeated and had to retreat north towards New York. Another colonial Group under the command of the Marquise de Lafayette cut the British off from New York. General Cornwallis was looking for a place for the British Navy to pick him up. He chose YORKTOWN.