age of naval warfare had arrived for the whole world. A new type of warship, monitor, was produced on the principle of the original. The use of a small number of very heavy guns, mounted so that they could fire in all directions, was first demonstrated by Monitor but soon became standard in warships of all types. Shipbuilders also incorporated rams into the designs of warship hulls for the rest of the century. Background Military situation The blockade at Norfolk On April 19, 1861, shortly after the outbreak of hostilities at Charleston Harbor, US President Abraham Lincoln proclaimed a blockade of ports in the seceded states. On April 27, after Virginia and North Carolina had also passed ordinances of secession, the blockade was extended to include their ports also. Even before the extension, local troops seized the Norfolk area and threatened the Gosport Navy Yard in Portsmouth. The commandant there, Captain Charles S. McCauley, though loyal to the Union, was immobilized by advice he received from his subordinate officers, most of whom were in favor of secession. Although he had orders from (Union) Secretary of the Navy Gideon Welles to move his ships to Northern ports, he refused to act until April 20, when he gave orders to scuttle the ships in the yard and destroy its facilities. At least nine ships were burned, among them the screw frigate . One (the old frigate ) was towed away successfully. Merrimack burned only to the waterline, however, and her engines were more or less intact. The destruction of the navy yard was mostly ineffective; in particular, the large drydock there was relatively undamaged and soon could be restored. Without firing a shot, the advocates of secession had gained for the South its largest navy yard, as well as the hull and engines of what would be in time its most famous warship. They had also seized more than a thousand heavy guns, plus gun carriages and large quantities of gunpowder. With Norfolk and its navy yard in Portsmouth, the Confederacy controlled the southern side of Hampton Roads. To prevent Union warships from attacking the yard, the Confederates set up batteries at Sewell's Point and Craney Island, at the juncture of the Elizabeth River with the James. (See map.) The Union retained possession of Fort Monroe, at Old Point Comfort on the Virginia Peninsula. They also held a small man-made island known