# Balilla-class submarine

The Balilla class were the first submarines to be built for the Italian navy following the end of World War I. They were large ocean-going cruiser submarines designed to operate in the Indian Ocean based in Italy's East African colonies. The design was double-hulled and based on the German Type UE II submarine U-boats, one of which, U-120 was supplied to the Italians as a war reparation. A 425 horsepower (317 kW) auxiliary diesel engine was installed as an extra generator.
During the war, the boats were stationed in the Mediterranean in 1940 but proved too large to be effective patrol submarines. Their only success was the sinking of the British submarine HMS Triad by Enrico Toti on 15 October 1940. After 1941 they were used as transport submarines to supply Italian forces in North Africa. The surviving boats were scrapped after the war.
One submarine, Humaytá, was built for the Brazilian Navy to a modified design.

## Design

The design of the Ballila class consisted of a strong double-hull which gave the ships a maximum diving depth of 110 m (350 ft), though Domenico Millelire reached 122 m (400 ft) in trials. The boats displaced 1,427 tons surfaced and 1874 tons submerged. They were 86.5 m (283 ft 10 in) long with a beam of 7.8 m (25 ft 7 in) and a draught of 4.7 m (15 ft 5 in). The boats were considered to have poor stability.
The submarines were powered by two Fiat diesels for surface cruising and two Savigliano electric motors for use while submerged driving two shafts. These created 4,900 bhp (3,700 kW) and 2,200 hp (1,600 kW) respectively. The second diesel engine was for auxiliary purposes and for recharging the batteries, novel at the time of the boats' construction. This gave the ships a speed of 16 knots (30 km/h; 18 mph) surfaced and 7 knots (13 km/h; 8.1 mph) submerged. However, the initial design called for the ability to reach speeds of 17.5 knots (32.4 km/h; 20.1 mph) surfaced and 8.9 knots (16.5 km/h; 10.2 mph) submerged; the subs never reached these marks. The Ballila-class boats had a range of 13,000 nmi (24,000 km; 15,000 mi) at 10 knots (19 km/h; 12 mph).
The Ballila class was armed with six 533 mm (21 in) torpedo tubes with four located in the bow and two in the stern. The submarines carried a load of 16 torpedoes, with two reloads for each bow tube and one reload for each stern tube.
The class was also armed with one 1924 model 120 mm (5 in)/27 calibre deck gun that was placed in a shielded mounting in the forward section of the conning tower. In 1934, the class underwent a refit that upgraded the model to a 120 mm (5 in)/45 calibre gun. The ships also received two 13.2 mm (0.52 in) machine guns placed two single mounts.

### Humaytá sub-class

Humaytá was ordered by the Brazilian navy as a deep-diving submarine. Modifications to the standard Ballila design include the placement of the diesel and electric motors further forward, the elimination of the bow planes and a different distribution of the ballast tanks throughout the submarine. The submarine was longer at 87 m (285 ft 5 in) with a shallower draught, 4 m (13 ft). The vessel displaced 1,390 tons surfaced and 1,884 tons submerged.
The submarine was powered by two Ansaldo diesels with one electric motor creating 4,900 bhp (3,700 kW) and 900 hp (670 kW) respectively. This gave the ship a speed of 18.5 knots (34.3 km/h; 21.3 mph) surfaced and 9.5 knots (17.6 km/h; 10.9 mph) submerged.
Humaytá differed in armament too. The submarine was equipped with the six 533 mm (21 in) torpedo tubes with four located in the bow and two in the stern. However, the vessel had only a 4 in (102 mm) deck gun and carried 16 mines.

## Ships

All ships were built by OTO in Muggiano. Humaytá was a modified version of this design built for the Brazilian Navy in 1927. The ship was retired in 1950.
Ship details :
| Ship | Namesake | Country | Launched | Fate |
| Balilla | Giovan Battista Perasso | Italy | 20 February 1927 | Transformed in barge and broken up in 1946 |
| Domenico Millelire | Domenico Millelire | Italy | 19 September 1927 | Turned into latex depot and used by Pirelli until 1977 |
| Antonio Sciesa | Amatore Sciesa | Italy | 12 August 1928 | Damaged September 1942 at Benghazi, scuttled 12 November 1942 |
| Enrico Toti | Enrico Toti | Italy | 14 April 1928 | Used as pontoon and broken up in 1946 |
| Humaytá | | Brazil | 11 June 1927 | Scrapped |