[3] Sited on the eastern tip of Oak Island in Brunswick County, NC, the fort juts into the confluence of the Cape Fear River and the Atlantic Ocean.

Typical of coastal southeastern North Carolina, the natural topography of the site is flat, roughly ten feet above sea level with a wide sandy beach along its southern boundary.

With over 61 gun emplacements, it guarded the mouth of the Cape Fear River in defense of Wilmington, then an important port 20 miles upriver and, at the time, the state's largest city.

In 1861, it was seized twice by a group called the "Cape Fear Minutemen", who were subsequently ordered by Governor John Willis Ellis to return it to the keeper of the fort, the only man stationed there by the U.S. Army at the time.

The loss of the Confederacy's last port was a major factor in Robert E. Lee's decision to surrender at Appomattox[5] The U.S. Army built a full military reservation on the site in the 1890s complete with coastal artillery batteries, and most of the buildings currently extant as well as the sea wall were constructed during this period.