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 Patriot 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.