The two Trafalgar-class battleships of the British Royal Navy were late-nineteenth-century ironclad warships.

Both were named after naval battles won by the British during the Napoleonic Wars under the command of Admiral Nelson.

They were originally intended to have a secondary armament of eight 5 inch guns but this was changed to six quick-firing 4.7 inch guns for use against attacking torpedo boats, which led to a weight increase of 60 tons, partly due to the increased amount of ammunition carried.

This was one of the changes which led to the vessels being 600 tons overweight, causing an increase in draught of a foot.

This design had been favoured for several years because it reduced the size of the target that the ships presented to enemy guns in battle, and because the smaller hull area allowed thicker armour.