 The casemate was heavily armored (later Confederate ironclads had three layers of steel) over heavy wood backing and was sloped to deflect direct hits (a 35-degree angle quickly becoming standard).Though deflection of the traditional round shot was the primary sloping rationale for ironclad designers, there actually was an added advantage involved, becoming more pertinent in the later stages of the war when armor penetrating ordnance was developed, especially by the Union Navy who at war's end had developed shells capable of penetrating up to of perpendicularly placed armor – hence the increase of armor thickness on Confederate ironclads; sloping increased effective armor thickness against armor piercing ordnance, which was typically fired on a flat trajectory.For example, the later Confederate armor, sloped at 35 degrees, resulted in a 22 percent increase of effective horizontal armor thickness at .