The Civil War saw more ironclads built by both sides , and they played an increasing role in the naval war alongside the unarmored warships , commerce raiders and blockade runners . The Union built a large fleet of fifty monitors modeled on their namesake . The Confederacy built ships designed as smaller versions of the Virginia , many of which saw action , but their attempts to buy ironclads overseas were frustrated as European nations confiscated ships being built for the Confederacy — especially in Russia , the only country to openly support the Union through the war . Only CSS Stonewall was completed , and she arrived in American waters just in time for the end of the war .