My humble submission (historical events apply to Thiariaverse):
Units in Class: Sicilia and Saradegna
Builder (Sardegna): OTO, La Spezia
Laid down: September 18th, 1936
Launched: July 20th, 1938
Completed: November 14th, 1940
Fate: Sunk as target, October 23rd, 1948
18.600 metric tons (standard); 23.150 metric tons (deep load)
204,90 meters (between perpendiculars); 215,50 meters (waterline); 231,00 meters (overall); 223,25 meters (flight deck)
21,50 meters (waterline); 24,50 meters (hull maximum including bulges) 29,00 meters (flight deck maximum); 39,20 meters (total maximum over crane sponsons)
6,40 meters (standard); 7,60 meters (deep load)
Twin shaft geared Belluzzo (Parsons type) turbines
Six Yarrow (license produced) boilers
Total power 100.000 shp
Top speed 31,5 knots (trial); 30,0 knots (six months out of dock); 28,0 knots (sustainable)
Range 5.250 nm @ 15 knots
1.150 Navy personnel (ship) + 650 Air Force personnel (air group)
80mm belt over machinery
50mm main armoured deck
20mm flight deck (partially, blast protection for 135mm guns)
100mm traverse bulkheads
40mm torpedo bulkheads (protective space 3,25 meters on either side in semi-recessed bulges)
100mm main gun turrets
60mm main gun barbettes
15mm HA gun and autocannon mounts
8 (4x2) 135mm/45 LA guns (1 director on top of bridge)
12 (12x1) 90mm/50 HA guns (4 directors, two on either beam)
16 (4x4) 37mm/60 AA autocannon (directors integrated in mounts)
2x 25m catapults
Up to 50 aircraft (normal operational complement 30 fighters and 12 torpedo bombers)
During the 1920s, Italy did not show much interest in aircraft carriers, because all air assets were assigned to the Air Force which vehemently resisted any attempt to form a naval air arm. As Italy mainly strove to maintain parity with France, and France’s sole carrier Bearn was too slow for proper fleet work, it was not considered necessary to follow up. A promising carrier design by an engineer named Bonfiglietti dating to 1929 was rejected for that reason. This changed when the French laid down their fast fleet carrier Neptune in 1930, mostly as a means of keeping their yards in business during the Great Depression. Lack of funds prevented any immediate Italian reaction, but Neptune’s very existence changed the game completely. Although she was never intended for service in the Mediterranean, she triggered the Italian decision not only to match the French carrier programme, but to outdo it. Therefore, even before Neptune was commissioned in 1937, the Italians approved and funded two fast fleet carriers of their own under the 1935 supplementary fleet building programme which also approved twelve Piemonte-class super destroyers. Unusually, the Navy would only provide the ship’s crew; the air group personnel was to be provided by the Air Force.
Lacking experience in carrier design, the Italians studied foreign projects. USS Ranger and the Thiarian Antartach were visited, and the Japanese allowed an Italian naval mission a yard tour to Soryu, then under construction. The Italians used the 1929 Bonfiglietti design as a basis, but increased her size to approximate Soryu’s. Machinery was taken from the contemporary Duca-degli-Abruzzi-class light cruiser, and protection was similar to that of the preceding Eugenio-di-Savoia-class. The whole package came out heavier and bulkier than Soryu, so bulges needed to be added, which in turn allowed installation of torpedo bulkheads. Anti-surface guns and catapults – both missing on Soryu – were considered crucial; if operating in the Mediterranean, neither sufficient maneuvering space to always turn into the wind nor sufficient wind to turn into could be taken for granted, and run-ins with enemy light surface forces could not be reliably avoiced. The original plan envisaged 152mm guns, but weight considerations dictated using lighter 135mm pieces. AA armament comprised 12 of the new stabilized 90mm cannon and four brand-new quad turrets of fully automatic 37mm AA cannon. The flight deck was offset from the ship’s centerline and widened to port amidships, both to create deck parking space and to balance the weight oft he island and the armoured LA gun turrets.
Both ships were laid down in March 1936, Sicilia at La Spezia and Sardegna at Livorno. Contractor for both was the OTO group, which had a reputation to build fast, although they had never built anything bigger than a heavy cruiser so far. Despite this lack of experience, they lived up to their reputation. Sicilia was launched in May 1938 and Sardegna in July. Deliveries of armament and catapults went ahead on schedule; arrestor gear and elevators were delivered from Thiaria under a contract struck in 1937. By late 1938, it had become evident that carrierborne planes would be a bottleneck. To provide state-of-the-art aviation, a carrier fighter and a torpedo bomber were to be custom designed; the fighter was awarded to IMAM, the bomber to Breda. Both companies based their planes upon existing designs, the Ro.51 and the Ba.65, repectively; they were however enlarged to provide the necessary range of 1.200 kilometers, which in case of the Ba.65 resulted in a complete re-design, which proved time-consuming in the extreme. To make matters worse, both types were to be powered by the same Fiat A.82 engines of 1.250 (prospectively up to 1.400) hp, which were still beta in 1938 and nowhere near maturity. The fighter (IMAM Ro.52) proved more manageable, because it was light enough to be fitted with a weaker, but reliable A.80 of 1.000 hp till the A.82 became available; the fighter was a robust and reliable design whose aft fuselage, tail and outer wings would later be recycled fort he Ro.57 twin engine strike fighter. The bomber’s (Ba.85) development however dragged on and on; overweight issues and problems with the undercarriage and . To provide the air groups with trained carrier pilots, the Italians procured 40 Martin T4M torpedo bombers in the USA, where the type was phased out in 1938; they all were at least seven years old by that time and structurally worn, but considered sufficient to develop torpedo attack tactics.
By the time Italy entered the war in 1940, the Air Force had formed twelve carrierborne squadriglie: Seven with ten fighters each (three with Ro.51s for training, four with the new Ro.52 for deployment); the remaining T4Ms were assigned to two operational and three training squadrigile of six machines each. Of the Ba.85, only three prototypes were flying (three more had crashed). Neither carrier was delivered prior to Italy’s entry into the war, and when they were commissioned in October and November 1940, respectively, Sicilia and Sardegna had to embark strike squadrons with ten-year old castoffs. Rather than their designed complement of three fighter and two torpedo strike squadriglie (their main role being fleet air defence), they had to make do with an understrength complement of obsolete machines and trainers.
Sardegna did not become fully operational till March 1941; by the time oft he raid on Taranto, she was in service for three days, conducting training off Genova. She also missed Italy’s botched attempt at vengeance off Matapan. At that time, at least all thirty Ro.52s were embarked; the strike component still flew the antique T4M. She had her combat debut off Crete in May 1941, supporting the invasion. At the first battle of Sirte in December 1941, both carriers were present with the Italian fleet, but Sicilia was torpedoed by HMS Upright, and Sardegna, through inept maneuvering, was caught in a melee with three British destroyers and a Recherchean light cruiser, and was barely able to escape after damaging the cruiser with her 135mm guns (and three Piemonte-class super destroyers coming to her aid, torpedoing and sinking one British destroyer and driving the enemy away). After that engagement, she was refitted with eight twin 20mm cannon. The first operational Ba.85 torpedo bombers were finally delivered, and during the second battle of Sirte in March 1942, Sardegna for the first time flew her designed air group. Although her planes achieved little (the Ba.85s were too heavy for Sardegna’s catapults, requiring conventional takeoff into the wind despite constant maneuvering to counter the submarine threat), the very presence of a substantial CAP over their fleet boosted Italian morale, and the Italian fleet for the first time used its numerical superiority to drive away the British convoy escort and scatter the convoy. After this battle, British Air Assets on Malta were depleted and needed replenishment; the RN twice sortied aircraft carriers (HMS Renown, HMS Furious and USS Wasp) loaded down with Spitfires to be flown from their decks to reinfore Malta. Sicilia and Sardegna sortied against both missions, resulting in savage air battles; although the Ro.52 were normally no match for a Spitfire V, the RAF planes were not navalized and much of their equipment malfunctioned (especially weapons and radios), causing high losses on both sides. After this failure, heavily shielded convoys to Malta were tried, but again intercepted by substantial Italian forces; convoys Harpoon, Vigorous and Pedestal were all heavily bloodied, in the last case following a full-blown naval battle which caused heavy RN ship losses. Again, Sicilia and Sardegna provided fleet air defence and did not launch strikes, but enabled the Italian surface fleet to come to grips with the RN in a daytime engagement at good visibility, negating most British technological advantages. After the scattering of Pedestal, Malta’s defenses were exhausted, and Operation Hercules commenced virtually immediately. Sicilia and Sardegna covered the Italian invasion forces against little resistance, and although the invasion met with complete success, Sardegna took a torpedo into the bow by HMS Unique (the british sub itself was sunk by the Italian destroyer Ascaro hours later) and needed to be towed to La Spezia for repairs.
The refit lasted seven months; the carrier was fitted with EC-3ter radar, a reverse-engineered HF/DF antenna, and another six twin 20mm cannon. During reconstruction of the bow, the catapults were replaced with longer, more powerful units not only able to shoot a Ba.85 at maximum weight, but also the upcoming Ca.360 twin-engined torpedo bomber expected early in 1944. To support the longer catapults, the bow was plated in and now resembled a RN hurricane bow. By the time Sardegna re-entered service in May 1943, the Allies had invaded North Africa and were driving for Tunis; Sardegna and Sicilia supported an Axis counteroffensive in June and August, which pushed the Allies back all the way to Alger, but overstretched the available forces during the inconclusive battle of Tbessa. An attempt to intercept a tactical US landing behind Axis lines at Bejala, 50 kilometers east of Alger, resulted in a major naval battle, which saw Sicilia lost to British Barracuda torpedo bombers from HMS Formidable and Victorious. Sardegna escaped, but her air group was badly decimated; she lost all her Ba.85 torpedo bombers in a futile attempt to hit the big US carrier Constellation. The Ro.52 fighters were useless by that time, and most of them were shot down by Seafires and Corsairs. The invasion succeeded, and fort he rest of the year, Axis forces in North Africa were rolled up by US forces from the west and British and Recherchean tanks from the east. Sardegna was meanwhile re-equipped with Fiat G.55RN fighters (equipped with folding wings and arrestor gear) and up-engined Ba.85bis (with the fully developed 1.400hp A.82 engine).
By the time Sardegna re-joined the fleet in August 1943, Italy’s fortunes were going downhill. The Libyan Oil fields were taken by the Rechercheans in October, and the Axis forces in North Africa were forced to surrender in November 1943. Before that happened, Sardegna covered the evacuation of several thousand German and Italian troops to Sicily against massive British air attack; her G.55s proved equal to the task and shot down over 40 British aircraft. During the following weeks, Sicily was subjected to intense bombardment in preparation for invasion; the Italian fleet was held back to oppose the invasion when it came. Unfortunately by that time, Italy’s oil supply had all but dried up, and when the invasion came in April 1944, it was virtually unopposed. There were a few half-hearted sorties, but so overwhelming was Allied superiority that the Italians quickly retreated every time (during the most violent of these engagements, Sardegna’s fighters could not prevent the loss of the flagship Roma despite shooting down 26 British aircraft). When the fascist regime fell in July, Sardegna belonged to the fleet that went over to the Allies. When the Germans attacked their former allies, Sardegna’s G.55s engaged them and shot down 13 Do217s; although the battleship Italia was nearly sunk and the cruiser Duca degli Abruzzi was blown up, the rest of the Italian fleet made it. The Allies commissioned some of the Italian cruisers and destroyers, but the capital ships were interned and disarmed. After the war, the Soviets showed keen interest in Sardegna, but when the prizes were divided up, she was awarded tot he Commonwealth and transferred to the Recherchean Navy. She reached Recherche in 1947 and was used for trials; late in 1948, she was sunk as a bombing target.
All things considered, Sicilia and Sardegna were remarkably effective designs for a first-time effort; they had flimsy protection, wasted a lot of weight on useless LA guns and had awkwardly placed HA directors with very limited arcs, but their aviation facilities worked well and they were good sea boats with comfortable accomodation. Although their strike aircraft never sank an enemy ship, their fighters accounted for 281 enemy airplanes between them, 194 of them shot down by Sardegna’s aircraft.