On 19 April 1861 Union President Abraham Lincoln declared a naval blockade on all Confederate ports. Lincoln hoped to block British imports, particularly weapons and ammunition, from reaching the Confederate nation. To break the blockade, the Confederate navy built ironclad "rams," ships protected by iron armor and designed to puncture large holes into old-fashioned wooden ships. Although the rams were modeled after the French and British prototypes, the Confederate government became the world's first belligerent to use them in naval warfare. The tengun C.S.S. Virginia moved against the Union blockade on 8 March 1862 at Hampton Roads, Virginia. (The ship was actually the converted U.S.S. Merrimac, a federal steamer captured by the Confederates after they seized the federal naval base at Norfolk, Virginia in April 1861). The Virginia quickly sank one Union ship by charging into it with its iron ram and...