A monitor is a class of relatively small warship that is lightly armoured, often provided with disproportionately large guns, and originally designed for coastal warfare. The term "monitor" grew to include breastwork monitors, the largest class of riverine warcraft known as river monitors, and was sometimes used as a generic term for any turreted ship. In the early 20th century, the term "monitor" included shallow-draft armoured shore bombardment vessels, particularly those of the Royal Navy: the Lord Clive-class monitors carried guns that fired the heaviest shells ever used at sea and saw action against German targets during World War I. Two small Royal Navy monitors from the First World War, Erebus and Terror survived to fight in the Second World War. When the requirement for shore supp