[Steel Wolf]

In 1861, Lincoln sent the Union army to Baltimore. Mayor Brown, the city council, and the police commissioner were arrested and imprisoned at Fort McHenry for the remainder of the war.

I don't think Fort McHenry is anything more than a tourist attraction anymore, so that's a historically accurate and legally vetted option for you. ;-)

[Bubba Ho-Tep]

In 1861, Lincoln sent the Union army to Baltimore. Mayor Brown, the city council, and the police commissioner were arrested and imprisoned at Fort McHenry for the remainder of the war.

Actually Brown and the others were all released by November, 1862. And most of them weren't held in Ft. McHenry. They were held in Ft. Warren in Boston.