France's entry into the Revolution in 1778 altered the entire nature of the conflict. No longer was the Revolution simply a conflict between Britain and the United States; the war quickly expanded to include a number of other major European powers. In 1779, Spain joined France, hoping to regain Gibraltar and the Floridas. And in late 1780, Britain declared war on the Netherlands, partly in order to cut off war supplies that were flowing to the Americans from a small Dutch island in the Caribbean.
Having failed to suppress the Revolution in the North, Britain redirected its attention to the South, which it believed would be easier to conquer. The British plan was to secure the major southern seaports at Savannah, Georgia, and Charleston, South Carolina, and to use these ports as bases for inland campaigns and for rallying southern loyalists.
In December 1778, a British force sailed from New York City and easily captured Savannah. Within months, the British army controlled all of Georgia. A joint French and American operation in October 1779 failed to drive the British from Savannah.
Early in 1780, British forces landed near Charleston, South Carolina. This letter by Henry Laurens (1724-1792) was written as British forces approached the city, which they captured in May, forcing the surrender of about 5,500 American soldiers.
So desperate was the situation that Laurens proposed arming 5000 slaves--a proposal ultimately blocked by the South Carolina legislature. Maintenance of the slave system was more important to the legislators than blocking the British invasion.
[F]rom the loud roaring of our approaching Enemy one would think So. Carolina...may be reduced to extreme poverty & other pains & penalties within ten days, but I hope better things & am in no fears save such as arise from considerations of the distresses of Women, Children aged & infirmed persons. For my own part I trust, that, "Although the fig trees shall not blossom, neither shall fruit be in the vines, the labor of the Olive shall fail, & the fields shall yield no meat, the stock shall be cut off from the Lord & there shall be no herd in the stalls, I will rejoice in the Lord I with joy in the God of my Salvation." I have not time to tell you whence I derived this pious Resolution, the sentiments have from youth upwards been strongly impressed upon my mind & appear in full force & vigor whenever danger appears. I pray God to bless you & all my friends in Congress--be assured.