Civil War - Monitor vs. Merrimack The battle on March 9, 1862, between the USS Monitor and the CSS Merrimack, officially the CSS Virginia, is one of the most revolutionary naval battles in world history. Up until that point, all battles had been waged between wooden ships. This was the first battle in maritime history that two ironclad ships waged war. The USS Merrimack was a Union frigate throughout most of its existence, up until the Union Navy abandoned the Norfolk Naval Yard. To prevent the Confederate Navy from using her against them, the Union Navy