On March 18th, two grenadier battalions left Fort Johnson and joined the forces at Hudson's House on James Island. The British had constructed a fort there and it was occupied by Maj. Thomas Mecan of the 23rd Regiment of Foot, and 120 men of the Hessian Regiment von Benning. By the next day, Hudson's house was surrounded by a breastwork 12-feet thick. Two redoubts were constructed 300 feet away from the fort, with abatis of sharpened apple and peach tree limbs. The left redoubt was on the Stono River and the right redoubt was on the Wappoo Canal. The fort was built to protect the British fleet and transport vessels on their approach to Charleston.

On March 21st, Hessian Capt. Johann Ewald conducted a reconnaissance of the Patriot lines and found the place where the main Patriot guard stationed himself. He also discovered the different paths of the guard posts, and then placed a corporal and five men on one of these paths. The men were to remain until they were able to ambush a returning Patriot guard.

About midnight, a party of dragoons rode up to the redoubts on the Wappoo Canal and fired their pistols. Upon their return the Hessians ambushed them. One sergeant major was wounded and captured.