The Adua-class submarines were essentially repeats of the preceding. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of. For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the Adua class had a range of at, submerged, they had a range of at. The boats were armed with six internal torpedo tubes, four in the bow and two in the stern. They were also armed with one Škoda 10 cm K10#OTO 100.2F47 History| deck gun for combat on the surface. The light anti-aircraft armament consisted of one or two pairs of Breda Model 1931 Machine Gun| machine guns.
Construction and Career
Alagi was built in the CRDA shipyard, in Monfalcone. She was laid down on 19 March 1936, launched 15 November of the same year, and commissioned on 6 March 1937. On May 11, 1937 Alagi was assigned to the 23rd Squadron based in Naples, from where she conducted training in the Dodecanese. During the Spanish Civil War, between 27 August and 4 September 1937, she carried out a special mission. In 1939 she was reassigned for some time to the base in Cagliari and then to Messina. In 1940 Alagi was assigned to 71st Squadron based at Cagliari. On 10 June 1940, at the outbreak of hostilities, Alagi was on patrol in the waters off Bizerta. She remained on station until June 20 without sighting any enemy ships. From June 5 to 11 of 1941, Alagi, under command of captain Giulio Contreas, patrolled 20 miles northeast of Ras Azzaz. She sighted a small enemy ship and tried to launch an attack, but it was interrupted by a second ship which detected Alagi and headed in her direction, forcing her to disengage. At 10:47 on June 12, 1941 while returning to Messina, Alagi was attacked with two bombs and machine guns off Benghazi by a British Sunderland aircraft. The boat's crew responded with anti-aircraft weapons forcing the plane to turn away, probably because it was hit. On July 18, 1941 she patrolled off of Cape Bougaroun. On July 22 she detected Force H but was unable to attack it, and was subject to anti-submarine search by escorts. During August 1941 Alagi patrolled between Sardinia and La Galite Island. She spent November and December 1941 patrolling off Cape Fer. In the late afternoon of January 14, 1942 in the Strait of Sicily, Alagi sighted a British naval formation and at 21:05 launched two torpedoes, which did not hit any targets. On 8 June 1942, roughly 20 nm North of Cape BonAlagi, under command of captain Sergio Puccini, fired three torpedoes at a naval column. One torpedo hit and sunk the Italian destroyer Antoniotto Usodimare in a friendly fire incident . On July 12, 1942 at 20:04 in the position, northwest of Tripoli, Syria, Alagi fired two torpedoes and scored one hit in the engine room of the Turkish tanker Antares on a trip from Iskanderun to Haifa, causing her to be beached on Ruad Island. The tanker was later re-floated, towed to Turkey and scrapped in late 1943. In August 1942Alagi operated along the Regia Marina and Luftwaffe to intercept and block an Allied convoy to Malta. On August 12, 1942 at 21:05 in the position Alagi fired a spread of 4 torpedoes against a merchant and a cruiser, and immediately dove. 3 explosions were heard. At 21:12 cruiser was hit forward by one of four torpedoes and sustained damage to bow structure. was able to make 25 knots and remained with the convoy to continue operating in defense of merchants. The other 2 torpedoes hit and sunk M/V Clan Ferguson which was previously damaged by a bomb from Ju 88. On November 8, 1942 while sailing submerged to her area of operation near Bizerta she collided underwater with another Italian submarine and suffered serious damage to her tower and had to turn back and return to Naples. In December she first patrolled between Cape Bougaroun, island of La Galite and Cape Fer and then from December 29 near Bona. In January 1943 Alagi patrolled northeast of Bona. From February through June 1943 she conducted several patrols south and southwest of Sardinia. In July 1943 Alagi first patrolled south of Sardinia, and later provided defensive screen in the waters of Sicily. On July 16, at 6:13 in the position she intercepted a column of three destroyers. Alagi launched three torpedoes while on surface. After a minute and 45 seconds a violent explosion was heard, but no information about this action was ever reported in British official documentation. On September 3, 1943 Alagi was deployed to the Gulf of Salerno, and on September 7, under the Zeta Plan, she was sent along with ten other submarines to the Tyrrhenian Sea, between the Gulf of Gaeta and the Gulf of Paola to intercept an anticipated Anglo-American landing in southern Italy. On September 9, 1943 following the announcement of the Armistice, Alagi which at that time was about sixty miles from Augusta headed for Malta, where she arrived on September 16, 1943 along with five other submarines escorted by destroyer. Upon arrival she surrender to the Allies. On October 13, 1943 Alagi together with fifteen other submarines left Malta for mainland Italy. In October 1943, Alagi was transferred to Haifa where she was employed as a training unit for British troops and as a shipping vessel for supplies to the Aegean Islands. She returned to Taranto in December 1944, where she remained inactive until the end of the war. She was sold for scrap on 1 February 1948.
