The Ironclad Board was an advisory board, established by the Union, in which year, in response to the construction of the "CSS Virginia" by the Confederacy during the US Civil War,primary goal of the Ironclad Board was to develop more battle-worthy ("ironclad") ships, including the USS Monitor, an iron-hulled steamship?
USS Monitor USS "Monitor" was an iron-hulled steamship. Built during the American Civil War, she was the first ironclad warship commissioned by the Union Navy. "Monitor" is most famous for her central role in the Battle of Hampton Roads on 9 March 1862, where, under the command of Lieutenant John Worden, she fought the casemate ironclad  (built on the hull of the former steam frigate USS "Merrimack" ) to a standstill. The unique design of the ship, distinguished by its revolving turret which was designed by American inventor Theodore Timby, was quickly duplicated and established the monitor type of warship.
USS Ajax (1864) Originally named USS "Manayunk, after a town in Pennsylvania, USS "Ajax was a single-turreted "Canonicus"-class monitor built for the Union Navy during the American Civil War. Completed after the end of the war, "Ajax" was laid up until 1871, although she received her new name in 1869. The ship was briefly activated in 1871 before a much longer commission began in 1874–75. She was assigned to the North Atlantic Squadron during this time. "Ajax" was again placed in reserve in 1891. The ship was on militia duty when the Spanish–American War began and she was recommissioned in 1898 to defend Baltimore, Maryland, although she was decommissioned later in the year before the necessary refit could be completed. "Ajax" was sold for scrap in 1899.