Sullivan’s Island sits on the North East entrance to Charleston Harbor, right beside the main shipping channel for large vessels coming into the port proper. Its geographic location makes it the perfect site to build a fort on the northern side of the harbor to protect this entrance. From this vantage point all shipping would have to come within range of its guns before passing into the harbor. On the Southern side of the harbor sits Fort Johnson which protects the Southern entrance to the harbor on James Island. This fort had been in service for many years on and off with the threat coming from the French and the Spanish for the decades. In 1775 there was no fortification on Sullivan’s Island and no need until the Colony decided to join the other colonies in breaking away from Britain. In January of 1775 a Provincial Congress was called for in South Carolina and it voted to break away from England and formed a rebel government in Charleston. As a result the Royal Governor Lord William Campbell escaped their capture by boarding one of the Royal Navy ships in the harbor for protection.
Here, in the harbor, Lord Campbell tried to continue Royal rule in South Carolina by trying to get Loyalist to rise up against the rebels and writing to General Howe in Boston and Lord North in London, England to send troops to retake Charleston for the crown. In his letters he told them of the Loyalist presence still in the colony that only need the support of Royal Troops to help them to rise up against the rebels. For months Lord Campbell wrote letters from the harbor to London and tried to secretly contact Loyalist in the interior of the colony to rise up against the rebels. The support of neither the Loyalist nor the Royal Troops materialized so he left with the Royal Navy leaving Charleston Harbor in the fall of 1775 and thus the last Royal presence in the colony left with him.
While this was playing out in South Carolina, General Howe and General Washington were in a stalemate in Boston before Howe left Boston with the British army and loyalist in March of 1776. With the stalemate going on in New England a plan was being formed by Lord North the Priminister of Great Britian and Lord Germain Secratory of State for the American Department in London on how to take back the colonies starting with the South and then like dominos moving northward to retake the colonies. This strategy was based upon the information give to them by the Royal Governor of South Carolina Campbell and North Carolina Josiah Martin. Their main contention was that if Royal troops came to the Carolinas that the Loyalist in great numbers would turn out in support of the King. This would allow the Royal troops to take an area and then the Loyalist could hold it as they moved to the next colony to subdue it. If this could happen then the rebellion could be put down quickly and his majesties power restored.