heavy cruiser

HMS Frobisher, a Hawkins-class cruiser around which the Washington Naval Treaty limits for heavy cruisers were written. A heavy cruiser was a type of cruiser, a naval warship designed for long range and high speed, armed generally with naval guns of roughly 203 mm (8 inches) in calibre, whose design parameters were dictated by the Washington Naval Treaty of 1922 and the London Naval Treaty of 1930. Heavy cruisers were generally larger, more heavily armed and more heavily armoured than light cruisers while being smaller, faster, and more lightly armed and armoured than battlecruisers and battleships. Heavy cruisers were not considered capital ships, unlike battlecruisers, battleships, and fleet carriers. Heavy cruisers were assigned a variety of roles ranging from commerce raiding to serving as 'cruiser-killers,' i.e. hunting and destroying similarly sized ships.

The heavy cruiser is part of a lineage of ship design from 1915 through the early 1950s, although the term "heavy cruiser" only came into formal use in 1930. The heavy cruiser's immediate precursors were the light cruiser designs of the 1900s and 1910s, rather than the armoured cruisers of the years before 1905. When the armoured cruiser was supplanted by the battlecruiser, an intermediate ship type between the battlecruiser and the light cruiser was found to be needed—one larger and more powerful than the light cruisers of a potential enemy but not as large and expensive as the battlecruiser so as to be built in sufficient numbers to protect merchant ships and serve in a number of combat theatres.