Obsolescence did not end every warship's usefulness

When did HMS Warrior and HMS Dreadnought become obsolete?

Warrior had little military use by about 1880, while Dreadnought left the front line around 1915 but retained secondary value through 1918.

Technological obsolescence differs from the complete disappearance of military utility. HMS Warrior's practical obsolescence came at roughly 1880. HMS Dreadnought was no longer desirable in the front line by about 1915, but could still perform duties such as convoy escort through the end of the First World War. The comparison shows why historians should ask what role an old ship can still perform rather than treating a newer design as an instant death sentence for every predecessor.