The Roberts class of monitors of the Royal Navy consisted of two heavily gunned vessels built during the Second World War. They were the Roberts, completed in 1941, and Abercrombie, completed in 1943.
Roberts-class monitor
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 and with limited use in the Second World War.
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