Trento made two extensive trips abroad, the first was a tour of South American countries in mid to late-1929 and the second was a deployment to China to protect Italian nationals during the Chinese Civil War.

Salvage operations began in 1950, and after it was determined that the ship's engines had been preserved by leaked fuel oil, the hull was sold to the Spanish Navy, which planned to convert the vessel into a light aircraft carrier.

[1] In 1924, the French Navy laid down the first of two Duquesne-class cruisers, prompting the Regia Marina to order two vessels to match their rival.

[4] While the ships were still on the slipways, officers in the Regia Marina expressed concerns that the thin armor protection of the Trentos would leave the vessels poorly equipped for combat.

[8] The ships were completed with a pair of tripod masts, though on trials they were found to vibrate excessively, and the foremast was strengthened with two extra legs.

They carried a pair of IMAM Ro.43 seaplanes for aerial reconnaissance; the hangar was located under the forecastle and a fixed catapult was mounted on the centerline at the bow.

[6] The turrets were arranged in superfiring pairs forward and aft, and allowed for elevation to 45 degrees, for a maximum range of 27,000 meters (30,000 yd).

The problem was in large part due to poor quality control in Italian munition factories, which failed to ensure tight manufacturing tolerances necessary for accurate shells.

[13] In addition, the single cradle mounts required the guns to be very close together; this caused the shells to interfere with each other in flight and contributed to the dispersion problem.

[11][17] Both vessels were protected with an armored citadel that covered the ships' vitals, including the machinery spaces and ammunition magazines.

During the pre-war period, Trento made lengthy trips abroad, including a tour of South America from May to October 1929 and a deployment to China from January to June 1932 to protect Italian nationals during the Chinese Civil War.

Both vessels took part in numerous naval reviews held for visiting foreign leaders in the 1930s, including Adolf Hitler of Nazi Germany and Miklós Horthy, the Regent of Hungary.

In 1938 Trieste helped transport soldiers of the Corpo Truppe Volontarie (Corps of Volunteer Troops), which had been sent to Spain to fight in the Spanish Civil War, back to Italy.

During one of the latter missions to attack the British Operation Harpoon convoy in June 1942, Trento was torpedoed twice, first by a Bristol Beaufighter torpedo bomber and then sunk by the submarine HMS Umbra with very heavy loss of life on 15 June;[25] out of a wartime complement of 51 officers and 1,100 enlisted men, 549 were killed in the sinking, and a further 21 later died of wounds.

Her superstructure was cut away and she was refloated and towed to La Spezia; an inspection revealed that fuel oil had leaked into the machinery spaces, protecting them while the ship had been submerged.

The Spanish Navy purchased the hull in 1952 and had her towed to Ferrol, with plans to convert the vessel into a light aircraft carrier.