 Unlike with turret ironclads, the guns had to fire through fixed gunports and therefore aiming was done by moving the gun relative to the gunport.This was labor-intensive and often up to 20 men were needed to load, aim, fire, and clean a gun, and even with this manpower the firing rate was no better than one shot per five minutes.Although the Union successfully used a substantial fleet of casemate ironclad riverboats in their Mississippi and Red River Campaigns, the casemate ironclad is mostly associated with the Confederacy.