The only monitor of the Monadnock-class to see action during the Civil War, the Monadnock was designed by Chief of the Bureau of Construction and Repair John Lenthall. Lenthall actually designed four monitors at that time. The Monadnock and the USS Agamenticus were the first and are considered the two Monadnock-class vessels. Lenthall altered the designs of the next two, the USS Miantonomoh and the USS Tonawanda and dubbed them the Miantonomoh-class. Because of the similarities between the two classes they are sometimes referred to collectively as the Miantonomoh-class.