The Roma-Class Battleship is a class of Battleship in use by the Regia Marina of the Kingdom of Italy. One of the most modern battleships currently in use in the world, and arguably the most modern battleship class in Europe(Though outclassed by the Iowa-Class Battleship in use the USA, and many different classes in use by the IJN), the Roma was commissioned to be built in 1938. However, due to budget constraints and no real need for large naval buildups, the first ship began construction in 1935.
Completed in 1939, the "Roma" was the first ship of the line and currently is the only one built, despite potential plans for two additional ships. Though lack of any threats has made the likelihood of this very small.
The ships' main battery consisted of nine 381 mm L/50 Ansaldo 1934 guns in three triple turrets, two in a superfiring pair forward and one aft. These long-barrel, high-velocity guns were chosen to compensate for the smaller 381 mm shell as compared to the 406 mm gun originally desired. The 381 mm guns had a maximum elevation of 35 degrees, which allowed them to engage targets out to 42,260 m (138,650 ft). The guns fired a 885 kg (1,951 lb) armor-piercing (AP) shell at a muzzle velocity of 870 meters per second (2,900 ft/s). High explosive shells weighed 774 kg (1,706 lb). The high muzzle velocity of the guns reduced their service life and increased the dispersion of the fall of shot. Shell rooms were located below the propellant magazines beneath the gun house in the turret structure. The guns' rate of fire was one shot every 45 seconds.
The ships' secondary battery consisted of twelve 152 mm (6.0 in) L/55 Ansaldo Model 1934 guns in four triple turrets. Two were placed abreast the No. 2 main battery turret and two on either side of the rear turret. These guns fired a 50 kg (110 lb) AP shell at a muzzle velocity of 910 m/s (3,000 ft/s). They could elevate to 45 degrees, permitting a maximum range of 25,740 m (84,450 ft). They had a rate of fire of slightly better than four rounds a minute. Four 120 mm (4.7 in) L/40 guns supplemented the 152 mm guns.
The ships' anti-aircraft armament was composed of a powerful battery of twelve 90 mm (3.5 in) L/50 guns closely arranged amidships, twenty 37 mm (1.5 in) L/54 guns, and sixteen 20 mm (0.79 in) L/65 guns. The 90 mm guns provided long-range anti-aircraft protection, and were mounted in quadriaxially stabilized single turrets. They had a rate of fire of 12 rounds per minute and had a ceiling of approximately 10,800 m (35,400 ft). The 37 mm and 20 mm guns were designed for close-range defense and had effective ranges of 4,000 m (13,000 ft) and 2,500 m (8,200 ft), respectively.
The ships' belt armor was designed to defeat 380 mm shells at ranges over 16,000 m (52,000 ft), and was inclined at 11 degrees. The belt was layered as follows: a 70 mm (2.8 in) hardened steel belt was used to de-cap armor-piercing projectiles. A 250 mm (9.8 in) wide gap separated the outer layer from the main belt armor, which was 280 mm (11 in) thick and was backed with 50 mm (2.0 in) of timber and 25 mm (0.98 in) skin plating. Another 140 mm (5.5 in) wide gap separated the main belt from a 36 mm (1.4 in) thick splinter screen. Another 25 mm thick screen was placed further inboard. The main section of the belt armor was closed on either end by 70 mm (2.8 in) thick transverse bulkheads. The bow was protected by a 60 mm (2.4 in) thick belt, while the stern was given 125 mm (4.9 in) of armor protection.
Horizontal protection over the magazine consisted of a 162 mm (6.4 in) thick armored deck. Over the machinery spaces, the deck was reduced in thickness to 110 mm (4.3 in), and on the outboard portions of the ships, the deck was reduced further to 90 mm (3.5 in). The aft steering rooms and auxiliary machinery spaces were protected by a 105 mm (4.1 in) thick deck. The main conning tower was protected by 50–130 mm thick side armor.
Above the deck, the main battery barbettes that housed the turret assemblies for the 381 mm guns were protected with 350 mm (14 in) thick armor, while below deck the thickness was reduced to 280 mm. The faces of the main battery turrets were 350 mm thick, with 200 mm (7.9 in) thick sides and roofs. The secondary gun turrets were housed in barbettes 150 mm (5.9 in) thick above deck and 100 mm (3.9 in) thick below deck. The turret faces were 280 mm thick, with 70 mm (2.8 in) thick sides. Below the third deck, neither the primary nor secondary barbettes were protected by armor. The anti-aircraft guns were protected with gun shields ranging in thickness from 12 mm (0.47 in) to 40 mm (1.6 in).