Light cruiser

The terms light cruiser and heavy cruiser were used in the interwar years, and during World War 2.

All the great powers agreed to tonnage limits, when the Washington Naval Treaty was signed, in 1920. The treaty set limits to the total tonnage for each class of ships, and maximum tonnages for each individual ship of each class.

The tonnage limit for treaty compliant cruisers was 10,000 tons. During this period almost all cruisers were armed with both banks of torpedoes, and a battery of cannons, of either six inches, or eight inches. Almost all cruisers had some armour, over and above the armour on their turrets.

Cruisers carrying batteries of eight inch cannons were called heavy cruisers, and they all displaced 10,000 tons. To maximize the number to treaty compliant cruisers some navies built light cruisers with a smaller number of six inch turrets. But, as war seemed more likely, all six inch light cruisers also diplaced the treaty limit of 10,000 tons.

The Japanese cruiser Moshami was built with five twin turrets, holding six inch guns, and was initially considered a light cruiser. After her six inch guns were replaced eigth inch guns, she was considered a heavy cruiser