The story of the most famous ship duel known to the history of the world, the battle between the _Monitor_ and the _Merrimac_, begins on June 10, 1861, when Lieut. John M. Brooke, C.S.N., formerly of the American navy, was assigned to assist the Confederate Navy Department in designing an ironclad that should be able to gain control of the navigable waters in and about the Chesapeake Bay. Brooke “entered upon this duty at once, and a few days thereafter submitted to the department, as the results of his investigations, rough drawings of a casemated vessel, with submerged ends and inclined iron-plated sides. The ends of the vessel and the eaves of the casemate, according to his plan, were to be submerged two feet; and a light bulwark or false bow was designed to divide the water and prevent it from banking up on the forward part of the shield with the vessel in motion, and also to serve as a tank to regulate the ship’s draft. His design was approved by the department,” and Constructor J. L. Porter was brought up from Norfolk to Richmond to assist in making the working drawings. Porter had already been considering this subject, and brought with him a model of a light-draft, screw-driven scow, that was to support a “casemated battery, with inclined iron-covered sides and ends.” In the opinion of Brooke this would have been, “for ordinary purposes, a good boat for harbor defence,” but a blunt-ended hull was, naturally, not to the liking of a naval man, and he proposed to have the ends of the hull “prolonged and shaped like those of any fast vessel, and submerged two feet under water, so that nothing was to be seen afloat but the shield itself.” Plans were drawn for such a ship, and, with Chief Engineer W. P. Williamson, Brooke went looking for engines to drive the proposed ironclad, but failed to find any. It was in this emergency that Williamson thought of the hulk of the _Merrimac_, that had been partly burned and sunk at Norfolk. Her engines were old and in bad order when she arrived at Norfolk before the trouble began, and new ones were to have been provided. Moreover, the fire and the soaking in sea-water had injured them; but Williamson knew that they could be made to work. Both Porter and Brooke “thought the draft too great, but were nevertheless of the opinion that it was the best thing that could be done,” and the order to transform the old frigate into a floating fort was issued. Williamson “thoroughly overhauled her engines, supplied deficiencies, and repaired defects, and improved greatly the motive power of the vessel.” Porter “cut the ship down, submerged her ends, performed all the duties of constructor, and originated all the interior arrangements.” The casemate was built according to the plans of his model.