Trieste had her
keel laid at the
Stabilimento Tecnico Triestino shipyard in
her namesake city on 22 June 1925. The completed
hull was
launched on 24 October 1926, a year before her
sister . After
fitting-out work was completed, the ship was
commissioned into the Italian fleet on 21 December 1928. On 16 May 1929 she joined
Trento in the newly created Cruiser Division for a cruise in the northern
Mediterranean Sea that lasted until 4 June. On 1 October,
Trieste became the
flagship of the 1st Squadron. In mid-1931, she entered the shipyard in
La Spezia for an overhaul that included the replacement of her tripod foremast with a more stable five-legged version. On 6 and 7 July 1933,
Trieste,
Trento, and the four s held a
naval review for the Italian dictator
Benito Mussolini in the
Gulf of Naples. On 2 December 1933,
Trieste,
Trento, and the heavy cruiser formed the 2nd Division of the 1st Squadron. The unit was renamed the 3rd Division in July 1934. On 18 June 1935,
Trieste temporarily relieved
Trento as the divisional flagship. Mussolini took a short tour of Italian Libya from 10 to 12 March 1937, and
Trieste was among the vessels to escort him. On 7 June, she took part in a major naval review held during the visit of German
Field Marshal Werner von Blomberg. The ship became the 2nd Squadron flagship on 15 February 1938. On 5 May, another naval review was held in the Gulf of Naples, this time for the
state visit of German dictator
Adolf Hitler. On 12 October 1938,
Trieste steamed out of
Messina with the 10th Destroyer Squadron, bound for
Cádiz, Spain. There, they met four Italian merchant ships on 15 October, which embarked 10,000 members of the
Corpo Truppe Volontarie (Corps of Volunteer Troops) that had been sent to support General
Francisco Franco's Nationalist forces during the
Spanish Civil War. The convoy left Cádiz on 16 October and arrived back in Naples on the 20th. On 17 May 1939,
Trieste took part in another fleet review, this one for
Prince Paul of Yugoslavia during his visit to Italy. From 5 to 19 June,
Trieste joined the rest of the fleet in
Livorno for the first celebration of
Navy Day on 10 June. From October to December, the ship underwent a major refit, which included modifications to her armament and the installation of
funnel caps.
World War II On 10 June 1940, Italy declared war on Britain and France, formally entering World War II. The heavy cruiser replaced
Trieste as the squadron flagship, which in turn became the flagship of the 3rd Division, which also included
Trento and
Bolzano. These four cruisers deployed north of Sicily to patrol for Allied vessels on Italy's first day of the war. On 31 August, the 3rd Division sortied to intercept the British convoy from Alexandria to
Malta in
Operation Hats, though the Italian fleet broke off the operation without encountering the merchant ships.
Trieste arrived back in Taranto on 2 September. She was present there on the night of 11–12 November, when the British
raided the port, and she emerged undamaged.
Trieste sortied with the fleet on 26 November in an attempt to intercept another convoy to Malta. The following morning, a reconnaissance floatplane from
Bolzano located the British squadron. Shortly after 12:00, Italian reconnaissance reports informed the Italian fleet commander,
Vice Admiral Inigo Campioni of the strength of the British fleet, and so he ordered his ships to disengage. By this time,
Trieste and the other heavy cruisers had already begun engaging their British counterparts in the
Battle of Cape Spartivento, and had scored two hits on the cruiser , the second of which is credited to either
Trieste or
Trento. The
battlecruiser intervened, and quickly straddled
Trieste twice, though the salvo inflicted only splinter damage. This compelled Campioni to commit the battleship , which in turn forced the British cruisers to break off the action, allowing both sides to disengage. On 9 February 1941,
Trieste sortied with the rest of the 2nd Squadron to search for
Force H after the latter had shelled
Genoa; the Italians returned to port without success. On 12–13 March,
Trieste escorted a fast convoy to North Africa.
Battle of Cape Matapan On 27 March, the division sortied with the rest of the fleet for a major sweep toward the island of Crete. During the operation,
Trieste flew the flag of
Rear Admiral Luigi Sansonetti. At 06:55 on the 28th, an IMAM Ro.43
floatplane launched by
Vittorio Veneto located a British cruiser squadron, and by 07:55,
Trieste and the 3rd Division had come within visual range. Seventeen minutes later, the Italian cruisers opened fire from a range of , initiating the first phase of the
Battle of Cape Matapan; in the span of the next forty minutes,
Trieste fired a total of 132
armor-piercing shells, though trouble with her
rangefinders and the extreme range of the action prevented her from scoring any significant hits. At 08:55, the Italian fleet commander,
Vice Admiral Angelo Iachino instructed Sansonetti to break off the action with the British cruisers and turn northwest, to lure the British vessels into range for
Vittorio Veneto. By about 11:00,
Vittorio Veneto had closed the distance enough to open fire, prompting Sansonetti to turn his three cruisers back to join the fight. The 6-inch-gun-armed British cruisers were outmatched both by the Italian heavy cruisers and
Vittorio Veneto, and they quickly reversed course. While the two sides were still maneuvering, a group of British torpedo bombers from Crete arrived and unsuccessfully attacked
Trieste and the rest of her division shortly after 12:00. Further attacks from the
aircraft carrier convinced Iachino to break off the action and withdraw at 12:20. Later in the day,
Vittorio Veneto and
Pola were torpedoed by British aircraft, the latter left immobilized.
Trieste,
Trento, and
Bolzano were also attacked by aircraft, but they escaped without damage.
Trieste reached Taranto in company with the damaged
Vittorio Veneto at 15:30 the following day. in the meantime,
Pola and two other
Zara-class cruisers were destroyed in the night action with British battleships late on the 28th.
Convoy operations From 24 to 30 April,
Trieste and
Bolzano escorted a convoy to North Africa. A combination of heavy seas and the presence of British warships forced the convoy to shelter in
Palermo, Messina, and
Augusta in Sicily before being able to make the crossing to Tripoli. A month later, the two cruisers covered another convoy; for the return leg of the voyage, the ships joined a second convoy also returning to Italy. Another convoy made the crossing on 8–9 June, again escorted by
Trieste and
Bolzano, along with the destroyers , , and .
Trieste and the heavy cruiser and the vessels of the 12th Destroyer Squadron covered four
ocean liners that had been converted into
troopships on 25 June; heavy British air attacks that night forced the convoy to return to Taranto. A second attempt was made on 27 June, and the ships successfully reached Tripoli on the morning of the 29th. Heavy air attacks targeted the ships while they were unloading the following day, but the ships were able to complete the task, depart that day, and reach Taranto on 1 July. From 16 to 20 July,
Trieste,
Bolzano,
Ascari,
Corazziere, and the destroyer covered another fast convoy to Tripoli. On 22 August,
Trieste sortied with other elements of the Italian fleet to try to locate Force H; they returned to port four days later empty handed. In late September, the British sent another convoy to reinforce Malta, codenamed
Operation Halberd; the Italian fleet sortied on 26 September to try to intercept it, but broke off the operation upon discovering the strength of the British escort force.
Trieste took part in the
Duisburg convoy on 8–9 November along with
Trento, the two ships serving as the convoy's covering force. The convoy was attacked by British warships in the early hours of 9 November, though the covering force failed to intervene and the convoy was destroyed.
Trieste escorted another convoy to Libya on 21 November in company with the light cruiser . Late that evening, the convoy came under a combined submarine and aircraft attack; at 23:12,
Trieste was torpedoed by the submarine , and a torpedo bomber hit
Duca degli Abruzzi shortly thereafter. The two damaged vessels were escorted back to Messina by the cruiser and the destroyer , arriving at around 08:00 the next morning. After repairs were completed,
Trieste joined
Bolzano and
Gorizia—the only other surviving heavy cruisers in the fleet—in the reorganized 3rd Division. The ships sortied with eight destroyers on 12 August 1942 to try to intercept a British convoy; while turning back after the operation was cancelled,
Bolzano and one of the destroyers were torpedoed by a British submarine.
Fate On 10 April 1943, while moored in
La Maddalena, Sardinia,
Trieste came under attack from
B-24 Liberator heavy bombers from the
United States Army Air Forces. She received several hits at 13:45, and at 16:13 she capsized to starboard and sank in the shallow water. Casualties were relatively light, with 66 men killed or missing—of those, three were officers, eight were
non-commissioned officers, and fifty-five were enlisted sailors—and 66 wounded—eight NCOs and fifty-eight sailors. The ship remained on the
naval register until 18 October 1946, when she was formally stricken. Salvage operations began in 1950, starting with the removal of the ship's superstructure. The hull was then made watertight, was refloated, still capsized, and was towed to La Spezia. There, the ship was righted, and upon inspection, the shipyard workers discovered that fuel oil that had leaked into the engine rooms had preserved the machinery. The
Spanish Navy purchased the hull and towed it to
Cartagena and then to
Ferrol in 1952 to convert
Trieste into a light aircraft carrier. The cost of the project proved to be prohibitive, and in 1956 the Spanish Navy sold the vessel for scrap; the ship was
broken up by 1959. ==Notes==