Heavy cruiser

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.

Casemate guns and a mixed battery were eliminated to make room for above deck torpedoes, and ever-increasing and more effective anti-aircraft armaments.

Their essential role had not changed since the age of sail—to serve on long-range missions, patrol for enemy warships and raid and defend commerce.

[2] Tactics and technology were gearing towards naval encounters held over increasingly longer ranges, which demanded an armament of primarily large calibre guns.

However, they were much larger, faster and better-armed than armoured cruisers, able to outpace them, stay out of range of their weapons and destroy them with relative impunity.

Because they carried the heavy guns normally ascribed to battleships, they could also theoretically hold their place in a battle line more readily than armoured cruisers and serve as the "battleship-cruiser" for which William Hovgaard had argued after Tsushima.

It also set the definition of a capital ship as a warship of more than 10,000 tons standard displacement or with armament of a calibre greater than 8 inches (203 mm).

To avert these challenges, representatives of the United States, Great Britain, Japan, France and Italy set limits on the tonnage and firepower of cruisers to 10,000 tons in standard displacement and 8 inches for maximum main gun caliber.

Planners in the U.S. Navy had spent two years prior to the start of negotiations designing 10,000 ton, 8-inch cruisers and were convinced that smaller vessels would not be worthwhile.

With battleships heavily regulated by the Washington Treaty, and aircraft carriers not yet mature, the cruiser question became the focus of naval affairs.

The British, with a strained economy and global commitments, favoured unlimited cruiser tonnage but strict limits on the individual ships.

The Japanese Myōkō class, however, grew during its construction as the naval general staff prevailed on the designers to increase the weapons load.

However, they were in effect a heavy cruiser being up gunned to 11-inch batteries at the cost of slower speed; their displacement was declared at 10,000 tons but was in practice considerably greater.

The Italian Navy first built two Trento-class cruisers, which sacrificed protection for speed, and then four Zara class, a much more balanced and better-protected design, plus an improved replica of the Trentos (Bolzano); all of them, however, surpassed the displacement limit.

Also, their unusual main battery layout and heavy tripod fore-masts made these ships top-heavy and prone to excessive rolling.

The solution the Japanese adopted was to build the Mogami class, which was declared as a 10,000 ton light cruiser with fifteen 6.1-inch guns.

[citation needed] The 1936 London Naval Treaty, principally negotiated between Britain and the United States but never ratified, would have abolished the heavy cruiser entirely by restricting new construction to 8,000 tons and 155 mm (6.1-inch) guns.

Heavy cruisers were still being built, and they could be balanced designs when nations decided to skirt the restrictions imposed by the London Naval Treaty.

The Des Moines class were the last heavy cruisers built: though based on the Baltimores, they were considerably heavier and longer due to their new rapid-firing 203 mm (8-inch) guns.

They resembled contemporary battlecruisers or battleships in general appearance, as well as having main armament and displacement equal or greater than that of capital ships of the First World War.

Furthermore the Alaskas lacked the sophisticated underwater protection system featured in battleships and battlecruisers, making them vulnerable to shells and torpedoes that hit under the waterline.

The Alaskas also had proportionately less weight in armour at 28.4% of displacement, in contrast to the British battlecruiser HMS Hood of 30%, the German Scharnhorst and the U.S. Navy's North Carolina-class battleships of 40%.

[9] Effectively, the Alaskas were ill-protected to stand up against the guns of true battleships and battlecruisers, and as carrier escorts they were much more expensive than the Baltimores while having only slightly better anti-aircraft capabilities.

Given low priority by the USN, only two members of the Alaskas were completed and they saw little service as World War II ended not long after their commissioning.