The USS Cincinnati was an American Cairo-class ironclad that was in service with the United States Navy in the mid-19th century. The Cincinnati participated in several river campaigns in the American Civil War, including the Battle of Fort Hindman, where it assisted in the shelling of the Confederate Army's Fort Hindman.
A print depicting this ship participating in the battle was stored in the USS Enterprise's library computer in 2254, and was among the materials viewed by the Talosians when they scanned the Enterprise computer. (TOS: "The Cage")
The Cincinnati was named for the American city Cincinnati.