A monitor is a relatively small warship that is neither fast nor strongly armored but carries disproportionately large guns. They were used by some navies from the 1860s, during the First World War an
USS Monitor, the first monitor (1861)
HMS Marshal Ney used a surplus 15-inch gun battleship turret.
Officers of a Union monitor, probably USS Sangamon, photographed during the American Civil War
Huáscar anchored in the harbour at Talcahuano
USS Monitor was an ironclad warship built for the United States Navy during the American Civil War and completed in early 1862, becoming the first such ship commissioned by the Navy. Monitor played a
Drawing of Monitor at sea
John Ericsson designed Monitor.