During World War II, both Conte di Cavour and her sister ship, Giulio Cesare, participated in the Battle of Calabria in July 1940, where the latter was lightly damaged.

For defense against torpedo boats, the ships carried fourteen 76.2-millimeter (3 in) guns; thirteen of these could be mounted on the turret tops, but they could also be positioned in 30 different locations, including some on the forecastle and upper decks.

In 1925–1926 the foremast was replaced by a four-legged (tetrapodal) mast, which was moved forward of the funnels,[9] the rangefinders were upgraded, and the ship was equipped to handle a Macchi M.18 seaplane mounted on the amidships turret.

[10][11][12] Conte di Cavour began an extensive reconstruction in October 1933 at the Cantieri Riuniti dell'Adriatico shipyard in Trieste that lasted until June 1937.

A major problem of the reconstruction was that the ship's increased draft meant that their waterline armor belt was almost completely submerged with any significant load.

[9] Admiral Paolo Thaon di Revel, the Italian naval chief of staff, believed that Austro-Hungarian submarines and minelayers could operate too effectively in the narrow waters of the Adriatic.

[21] Instead, Revel decided to implement a blockade at the relatively safer southern end of the Adriatic with the battle fleet, while smaller vessels, such as MAS torpedo boats, conducted raids on Austro-Hungarian ships and installations.

Conte di Cavour bombarded the main town on the island with her 76 mm guns,[23] killing 20 civilians and wounding 32.

[24] She escorted King Victor Emmanuel III and his wife aboard Dante Alighieri on a state visit to Spain in 1924, and was placed in reserve upon her return until 1926, when, in April, she conveyed Mussolini on a voyage to Libya.

They were part of the 1st Battle Squadron, commanded by Admiral Inigo Campioni, when they engaged major elements of the British Mediterranean Fleet.

Vice Admiral Andrew Cunningham, commander of the Mediterranean Fleet, attempted to interpose his ships between the Italians and their base at Taranto.

Crews on the fleets spotted each other in the middle of the afternoon and the Italian battleships opened fire at 15:53 at a range of nearly 27,000 meters (29,000 yd).

Three minutes after she opened fire, shells from Giulio Cesare began to straddle Warspite which made a small turn and increased speed, to throw off the Italian ship's aim, at 16:00.

Uncertain how severe the damage was, Campioni ordered his battleships to turn away in the face of superior British numbers and they successfully disengaged.

[26] On the night of 11 November 1940, Conte di Cavour was at anchor in Taranto harbor when she was attacked, along with several other warships, by 21 Fairey Swordfish torpedo bombers from the British aircraft carrier HMS Illustrious.

The ship's gunners shot down one Swordfish shortly after the aircraft dropped its torpedo, but it exploded underneath 'B' turret at 23:15, knocking out the main bow pump.

Some 15,000 long tons (15,000 t) of water were pumped out before Conte di Cavour was refloated on 9 June and entered the ex-Austro-Hungarian floating dry dock GO-12 on 12 July.

[28] Her guns were operable by September 1942, but replacing her entire electrical system took longer so the navy took advantage of the delays and incorporated some modifications to reduce the likelihood of flooding based on lessons learned from the attack.