When did the Federals learn of the fortifications at the northern NC inlets?

There was no blockade of North Carolina ports prior to July of 1861. On 1 July 1861, Flog Officer Stringham (commander of the Atlantic Blockading Squadron) reported that “the department will see that I have not one steamer or vessel at my command for the coast of North Carolina.” That changed rapidly the following week.

The USS Quaker City, cruising off Cape Henry, discovered a small sailboat containing seven men. Five of the seven were Northern men who had been residing in Washington, NC, pursuing their occupations as mechanics. Fearing for their safety, they escaped with the help of two local men with Union men from the area. During the course of their navigations to escape, they observed small forces of North Carolina rebels with light batteries at the various inlets. This was reported to Flag Officer Stringham aboard the USS Minnesota at Hampton Roads.

On July 4th, Welles received a letter forwarded by Secretary of the Navy Gideon Welles written by Peter Wilson of Wilmington reporting on the commerce being carried on through the port of Wilmington. He reported 8-10 vessels having cleared the port and no notification of the blockade as of 12 June 1861. Welles ordered Stringham to “dispatch the Roanoke without delay to the coast of North Carolina.” If necessary, Stringham was to send the Cumberland down as well until other ships became available.

The Roanoke sailed from Hampton Roads July 8th, followed by the Cumberland on the 9th. The USS Daylight left the morning of the 10th, followed by the USS Albatross the afternoon of that same day. In a report dated 14 July 1861, Flag Officer G. J. Pendergrast aboard the Roanoke alerted Stringham of an encampment a few miles north of Bodie’s lighthouse near Oregon Inlet. July 10th, the Roanoke discovered a battery at Hatteras Inlet. After an inconsequential exchange of shots, the Roanoke continued southward towards Wilmington to check the situation there.

In the meantime, the Daylight and the Albatross discovered the encampment and battery under construction at Oregon Inlet on July 11th. They shelled the camp and battery heavily, causing the laborers and soldiers alike to flee. Only 14 men were left to report for duty the next day. The fortification of the northern inlets on the North Carolina coast had been discovered and blockading ships had been put in place to enforce the blockade.