presence was sufficient to close the James River to Federal incursions. She also imposed other constraints on the Peninsula Campaign then being mounted by the Union Army under General George B. McClellan, who worried that she could interfere with his positions on the York River. Although his fears were baseless, they continued to affect the movements of his army until Virginia was destroyed. Impact upon naval warfare Both days of the battle attracted attention from almost all the world's navies. USS Monitor became the prototype for the monitor warship type. She thus became the first of two ships whose names were applied to entire classes of their successors, the other being . Many more were built, including river monitors, and they played key roles in Civil War battles on the Mississippi and James rivers. The US immediately started the construction of ten more monitors based on Ericsson's original larger plan, known as the s. More than 20 additional monitors were built by the Union by the end of the war. However, while the design proved exceptionally well-suited for river combat, the low profile and heavy turret caused poor seaworthiness in rough waters. Russia, fearing that the American Civil War would spill into Russian Alaska, launched ten sister ships, as soon as Ericsson's plans reached St. Petersburg. What followed has been described as "Monitor mania". The revolving turret later inspired similar designs for future warships, which eventually became the modern battleship. The vulnerability of wooden hulls to armored ships was noted particularly in Britain and France, where the wisdom of the planned conversion of the battle fleet to armor was given a powerful demonstration. Another feature that was emulated was not so successful. Impressed by the ease with which Virginia had sunk Cumberland, naval architects began to incorporate rams into their hull designs. The first purpose-built ram in the modern era was the French armored ram Taureau (1863), whose guns were said to have "the sole function of preparing the way for the ram." The inclusion of rams in warship hull design persisted almost to the outbreak of World War I. Commemorating the battle: Virginia The name of the warship that served the Confederacy in the Battle of Hampton Roads has been a continuing source of confusion and some contention. She was originally a screw frigate in the United States Navy carrying the name . All parties continued to use the