Impero was the fourth built for Italy's Regia Marina (Royal Navy) during the Second World War. She was named after the Italian word for "empire", in this case referring to the newly (1936) conquered Italian Empire in East Africa (Somaliland, Eritrea and Ethiopia territories) as a result of the Second Italo-Abyssinian War. She was constructed under the order of the 1938 Naval Expansion Program, along with her sister ship Roma.
Impero was laid down in May 1938 and launched in November 1939. The entrance of Italy into World War II forced the Regia Marina to refocus its construction priorities on escort warships, so Impero was left incomplete. After Italy surrendered to the Allies on 8 September 1943, the rest of the Italian Navy steamed to Sardinia to rendezvous with their American contemporaries. Still incomplete in Trieste, Impero was captured by the Germans, who used the hulk for target practice. Sunk by Allied bombers in February 1945, she was refloated in 1947 and scrapped in Venice from 1948 to 1950.
Background
The Italian leader Benito Mussolini did not authorize any large naval rearmament until 1933. Once he did, two old battleships of the were sent to be modernized in the same year, and and were laid down in 1934. In May 1935, the Italian Naval Ministry began preparing for a five-year naval building program that would include four battleships, three aircraft carriers, four cruisers, fifty-four submarines, and forty smaller ships. In December 1935, Admiral Domenico Cavagnari proposed to Mussolini that, among other things, two more battleships of the Littorio class be built to attempt to counter a possible Franco-British alliance—if the two countries combined forces, they would easily outnumber the Italian fleet. Mussolini postponed his decision, but later authorized planning for the two ships in January 1937 for the 1938 Naval Expansion Program. In December, they were approved and money was appropriated for them; they were named and Impero.
Description
Impero was long overall and had a beam of and a draft of . She was designed with a standard displacement of , a violation of the restriction of the Washington Naval Treaty; at full combat loading, she displaced . The ship was to be powered by four Belluzo geared steam turbines rated at . Steam was provided by eight oil-fired Yarrow boilers. The engines provided a top speed of and a range of at . Impero would have had a crew of 1,830 to 1,950 if she had been completed.
Imperos main armament would have consisted of nine 50-caliber Model 1934 guns in three triple turrets; two turrets were placed forward in a superfiring arrangement and the third was located aft. Her secondary anti-surface armament would have consisted of twelve 55-caliber Model 1934/35 guns in four triple turrets amidships. These were to be supplemented by four 40-caliber Model 1891/92 guns in single mounts; these guns were old weapons and were primarily intended to fire star shells. Impero was intended to be equipped with an anti-aircraft battery that comprised twelve 50-caliber Model 1938 guns in single mounts, twenty 54-caliber guns in eight twin and four single mounts, and sixteen 65-caliber guns in eight twin mounts.
The ship was protected by a main armor belt that was with a second layer of steel that was thick. The main deck was thick in the central area of the ship and reduced to in less critical areas. The main battery turrets were thick and the lower turret structure was housed in barbettes that were also 350 mm thick. The secondary turrets had 280 mm thick faces and the conning tower had thick sides. Impero was to be fitted with a catapult on her stern and equipped with three IMAM Ro.43 reconnaissance float planes or Reggiane Re.2000 fighters.