 The first use of ironclads in action came in the U.S. Civil War . The U.S. Navy at the time the war broke out had no ironclads , its most powerful ships being six steam @-@ powered unarmoured frigates . Since the bulk of the Navy remained loyal to the Union , the Confederacy sought to gain advantage in the naval conflict by acquiring modern armored ships . In May 1861 , the Confederate Congress voted that $ 2 million be appropriated for the purchase of ironclads from overseas , and in July and August 1861 the Confederacy started work on construction and converting wooden ships . 
