The breastwork monitor was developed during the 1860s by Sir Edward Reed, Chief Constructor of the Royal Navy, as an improvement of the basic monitor design developed by John Ericsson during the American Civil War. Reed gave these ships a superstructure to increase seaworthiness and raise the freeboard of the gun turrets so they could be worked in all weathers. The superstructure was armoured to protect the bases of the turrets, the funnels and the ventilator ducts in what he termed a breastwork. The ships were conceived as harbour defence ships with little need to leave port. This meant that they could dispense with the masts, sails and rigging needed to supplement their coal-fired steam engines over any distance. Reed took advantage of the lack of masts and designed the ships with one tw