Zara-class cruiser

The Zara-class was an Italian heavy cruiser design of the Regia Marina from the early 1930s, considered by many to be one of the best cruiser designs of World War II. Four ships of the class were completed, Zara, Fiume, Pola and Gorizia, all of which saw extensive service during the war.

Design
The Zaras were essentially an improved Trento class tasked with dealing with the latest French designs.

The Trentos had been designed to the limitations of the Washington Naval Treaty, which stated that cruisers had to be 10,000 tons or less, and armed with 8 in guns or smaller. The weight limitation made it impossible to design a ship with those guns and armour able to stop shells of the same caliber. A typical Washington design had 76 mm in its armour belt, and less on other areas of the ship. These thicknesses were reasonably good against destroyer and light cruiser weapons (typically between 5 in {127 mm} and 6 in {150 mm}), but insufficient against the 120 kg shells that 203 mm fired, capable of piercing even 150 mm at medium range. In general, in order to be effective, armour should be roughly the same thickness as the diameter of the shells fired against it.

Trentos had sacrificed armor for speed, allowing them to make high-speed dashes up and down the long Italian coastline, which would otherwise be difficult to defend from Italy's widely separated naval bases. Although equipped with powerful armament, hits against them would likely penetrate the armour and knock the ships out of combat. Even a won battle might seriously deplete Italian naval strength, something they were not prepared to address through sheer numbers.

The solution was a new design, one combining the armament of the Trentos with the armour needed to protect them from similar French designs. To achieve this, the Zaras were almost 2000 t (at standard displacement) over the 10,000 ton limit, even if fully loaded (because the modest amount of the fuel load) they displaced no more than, for example, British heavy cruisers. Extras such as a high superstructure and torpedo tubes were removed in an effort to save weight, but in the end the ships ended up considerably "overweight" anyway. The removal of the superstructure made placement of radar difficult, and in the end none of the class would ever carry one. This would prove to be a fatal omission.

Armour
The Zaras almost doubled belt armour compared to the Trentos, with 150 mm in the main belt. The main deck was also very thick, 70 mm. Turrets and barbettes were as well protected by over 100 mm armour. In addition to the primary armour scheme, there was secondary armour: the upper deck was 20mm, and the flank hull above main belt was 30 mm. Almost no other cruisers were equipped with two armoured decks and two armoured belts. This scheme followed, in fact, not quite a cruiser layout, but that of a small battleship. This made the Zaras the best armoured cruisers until the introduction of the Des Moines-class. This additional armour would have made the ships decidedly nose-heavy, so to offset this the rear of the ship was raised by one deck behind the front funnel. The result was excellent watertight integrity and protection.

Armament
The Zaras shared their main armament with the last of the three Trentos, the Bolzano. They were equipped with the 203 mm/L53 (8 in) guns of 25 tonnes each and were fitted in pairs in Ansaldo turrets. The guns had a high muzzle velocity of 939 m/s (3,080 ft/s) with a 125 kg (275 lb) AP shell, allowing Zaras to engage equals at a very long 34,400 yards (31,500 m) at 45 elevation. The Trento and Trieste had a less advanced model, firing a 110 kg to 29,000 m. The downside to the new gun was a greater dispersion of shots and barrel wear than normal.

The secondary armament was superior as well, compared to the standard of those times: sixteen Škoda Model 1910 100 mm/L50 guns were fitted in eight dual turrets, four on each side, again following a scheme similar to a small battleship. Later, these were replaced by OTO L/47s, plus two single 100 mm mounts for flare illumination rounds. In 1937, the aft 100 mm mounts were replaced by 37 mm/54 caliber Bredas more useful for close defense, and in 1940, the 40 mm Vickers were replaced by 37 mm Bredas, also. All these guns were reasonably modern, especially at their time, even if not outstanding performers. However, overall anti-aircraft performance was not good, due to the slow tracking process and an inadequate fire control system, although the weapons were acceptable.

One odd feature was the aircraft catapult on the bow, which made it impossible to prepare for launch while firing, perhaps a minor consideration. The Piaggio P.6bis originally carried was later replaced by M.41s, CANT 25ARs, MF6s, and in 1938, by Ro.43s.

Service history
Zara was laid down at OTO Muggiano 4 July 1929, launched 27 April 1930, and commissioned 21 October 1931. She was joined by Fiume, laid down at Stabilimento Tecnico Triestino on 29 April 1929, launched 27 April 1930, and completed 23 November 1931; Pola at OTO Livorno, laid 17 March 1931, launched 5 December 1931, and completed 21 December 1931; and Gorizia, launched 28 December 1930 at OTO Livorno.

France immediately responded with a new heavy cruiser of her own, Algérie, which was a close match for the Zaras when she launched in 1934.

When the Second World War broke out, Gorizia, Zara, and Fiume were organized into 1st Cruiser division, Pola serving as flagship for 2nd Cruiser Division. During this part of the war, the Zaras were a serious problem for the Royal Navy, which had nothing comparable in the Mediterranean Sea, and were seriously outgunned by them during the inconclusive Battle of Calabria and Battle of Cape Spartivento.

However, Zaras were eventually taken to task during the Battle of Cape Matapan. After Pola (in company with Fiume and Zara, serving as escort to the battleship Vittorio Veneto) was hit by a torpedo from a TSR Swordfish from Formidable, which stopped her, the rest of the 1st Division (at this time Gorizia was in reserve) ran in to protect her. Three Royal Navy battleships (the Queen Elizabeth-class sisters Barham, Valiant, and Warspite), plus many supporting units, were able to approach them closely at night &mdash; the lack of radar on Zaras making them unaware of their approach. Valiant, astonishingly, scored with her first salvo. The British battleships quickly sank all three Italian cruisers and two of their escorting destroyers in a one-sided gunfight, the only reaction being the aimless fire of a 40mm AA cannon from the already wrecked Zara.

Gorizia survived until she was taken over by the Germans after Italy left the war in 1943. In that year, her armour had the only opportunity to display its effectiveness, when this ship was hit by three bombs, launched by American bombers, but the main deck resisted them all and the ship continued to fire against the high-flying bombers. Later she was able to reach La Spezia, but the damage to the mid-ship was heavy, with almost all the structures over the armor belt devastated and a 100 mm (3.9 in) turret thrown into the sea. Ironically, at beginning of 1941, a modest British attack, at night, over Naples hit Zara. There were only two 113 kg (250 lb) bombs, launched at low altitude, but they pierced the hull and almost sank the ship. Gorizia was sunk 26 June 1944 at her moorings in La Spezia, in yet another twist of fate by Italian manned torpedoes, after the Italians joined the Allies.

Popular Culture
Two of the Class, the Zara and Pola, appeared in the alternate history Japanese anime Strike Witches 2 episode "Higher than the Sky". The ships were recreated in detail with CGI animation technology.