 At that time, Union naval forces in the sounds were threatened by the Confederate ironclad ram, "Albemarle", which in April had sunk Union side wheel steamer, , and had enabled Southern forces to recapture Plymouth, North Carolina.On the 20th, "Shamrock" reached Hatteras Inlet where orders awaited her to enter Albemarle Sound and take station off the mouth of the Roanoke River to guard against the reappearance of the formidable Rebel ram.For the next four months, "Shamrock's" operations concentrated on protecting Union shipping from "Albemarle", which was undergoing repairs up the Roanoke River.