The casemate ironclad was a type of iron or iron-armored gunboat briefly used in the American Civil War by both the Confederate States Navy and the Union Navy. Unlike a monitor-type ironclad which carried its armament encased in a separate armored gun deck/turret, it exhibited a single (often sloped) casemate structure, or armored citadel, on the main deck housing the entire gun battery. As the guns were carried on the top of the ship yet still fired through fixed gunports, the casemate ironclad is seen as an intermediate stage between the traditional broadside frigate and modern warships.