[Bubba Ho-Tep]

Yes the Harriet Lane stopped the Nashville before letting it proceed.

No. The Nashville was not flying any flag. The Harriet Lane fired a shot across her bow and she raised the US flag in response. She was never stopped.

[PeaRidge]

The Nashville was a very well known steamship that for years had carried passengers, goods, and the US Mail on runs from New York and Europe to southern ports, particularly Charleston.

In the late 1850s, she was making weekly runs. Her profile and schedule were well known to the Union navy, and particularly to the Revenue cutters.

As she attempted to enter the harbor, the Harriet Lane fired across her bow. She stopped.