A century-and-a-half ago, as the divided nation was engaged in the bitter Civil War, the fields of battle included not only land but also the sea. In response to President Abraham Lincoln’s declaration of a naval blockade of the Southern coast from Virginia to the Gulf of Mexico, the U.S. Navy began a buildup to enforce it. Off Hampton Roads, Virginia, the Navy’s ships were in a position not only to blockade, but potentially to enter the James River and push up to the Confederate capital of Richmond. The Confederates blocked the river with sunken ships and other obstructions, including underwater mines then known as torpedoes. They also raised and repaired the half-burned and sunken hulk of the former USS Merrimack , converting it into a new type of ironclad warship. Commissioned as the CSS Virginia , on 8 March 1862, the ironclad wreaked havoc on the Union Fleet at Hampton Roads.