A small, overgrown brick fort in Charleston Harbor that is sometimes confused with Fort Sumter also played a role in the opening of the Civil War and should be preserved, according to a historian studying the site.

Castle Pinckney, finished in 1809, is located on an island across the channel from Fort Sumter, where the opening shots of the Civil War were fired in April 1861.

Before the bombardment, Pinckney was seized by 150 Confederate forces without a fight, making it, not Sumter, the first Union fortification lost in the war, said Christopher Ziegler, a historian with the National Park Service.

Ziegler said the fort should be designated a national landmark.

It is one of only three similar forts of its era still standing — the other two are in New York — and was at one time a national monument.

The National Park Service never rehabilitated it, using it mostly for storage before giving it to the state.

Castle Pinckney is listed on the National Register of Historic Places.

“Pretty much everything that was there when the war ended is still there,” Ziegler said.

Castle Pinckney is now owned by the State Ports Authority.

The agency has done some small things to preserve it, but lacks the money and the mandate to conduct significant work there.

The shoreline of the island is eroding and has been protected by large rocks. Ziegler said the property should be analyzed by an engineer to see if it’s stable or needs urgent repair.

The interior has filled in with dirt, which later sprouted trees and shrubs.

“Let’s at least go out there and make sure nothing bad is happening,” Ziegler said.