R. Smg. Diamante

Diamante was a Sirena class coastal submarine (680 tons displacement on the surface, 850 submerged). It completed only one war patrol, covering 700 miles on the surface and 300 miles submerged.

R.Smg. Diamante

Brief and Partial Chronology

May 11th, 1931

Set-up began in the Tosi shipyards in Taranto.

May 21st, 1933

Diamante was launched at the Tosi shipyard in Taranto.

The launch of the Diamante

November 18th, 1933

Official entry into service, thereafter the boat was assigned to the submarine base in Taranto.


Diamante made a training cruise in the Eastern Mediterranean, stopping in Greece, the Dodecanese, Palestine, and North Africa. The boat ended the cruise in Messina, where it joined the VII Submarine Squadron. The captain of the boat was the Lieutenant Commander Costanzo Casana.


Located in Leros. After completing another cruise, it was transferred to Taranto.

January 12th, 1937

Assigned to the VI Submarine Group of Leros, Diamante sails from Naples under the command of Lieutenant Commander Andrea Gasparini for a “special” mission in the waters of Valencia against traffic directed to the ports of republican Spain in the context of the Spanish Civil War, in support of the Spanish nationalist forces. An officer of the Spanish Nationalist Navy, Lieutenant Luis Cebreiro Blanco, was on board for the occasion as liaison officer and to assist in the recognition of Spanish ships.

During the mission, Diamante began eight attack maneuvers, but the extremely restrictive rules of engagement – no neutral ships should be attacked unless they were engaged in smuggling in favor of the Republicans, and absolutely no recognition should be made because the Italian involvement in the conflict was secret and completely illegal – meant that only one of them was carried out.

January 16th, 1937

At 06:00 AM, Diamante, while on the surface, attacked a steamer with the launch of two torpedoes (one 450 mm and one 533 mm) and a cannon shot, without being able to hit the target.

January 28th, 1937

Diamante concludes the mission by returning to Naples. it encountered good weather and spent 173 hours on the surface and 124 submerged.


Located in Leros.

August 21st, 1937

Assigned to the IV Submarine Group of Taranto, Diamante sailed from Leros under the command of Lieutenant Commander Mario Tabucchi for a second special mission in the context of the Spanish war, this time in the Aegean Sea as part of a widespread blockade organized throughout the Mediterranean against traffic directed towards the ports of Republican Spain.

During the mission, Diamante initiates six attack maneuvers, but interrupts all of them before arriving at the launch.

August 31st, 1937

Diamante concluded the mission by returning to Leros, after spending 118 hours on the surface and 124.05 submerged, covering 794 miles on the surface and 340.5 submerged.

September 5th, 1937

Still under the command of Lieutenant Commander Mario Tabucchi and under the command of the IV Grupsom of Taranto, Diamante departs from Leros for its third and last special mission (again in the Aegean) during the Spanish Civil War.

During the mission, it encountered rough seas and bad weather and began 16 attack maneuvers, all of which were interrupted before arriving at launch.

September 13th, 1937

Diamante returned to Leros, concluding the mission after 90 hours spent on the surface and 84 hours underwater (he covered 609.5 nautical miles on the surface and 232.5 submerged).


Assigned to the XII Submarine Squadron, based in La Spezia.

February 1939

Located in Tobruk, which was its base until the loss.

March 24th, 1940

Lieutenant Angelo Parla, 32, from Licata, took command of Diamante. He will be the last commander.

Another picture of Diamante

June 1940

Shortly before Italy’s entry into the war, Diamante was based in Tobruk, under the command of Lieutenant Angelo Parla, within the LXII Submarine Squadron (which he formed together with Topazio, Nereide, Galatea and Lafolè), part of the VI Submarine Group.

The first, and last, patrol

Already at 06:00 PM of June 9th, 1940, the day before Italy entered World War II, Diamante left Tobruk under the command of Lieutenant Angelo Parla to carry out its first war patrol in the waters of Libya: the boat, together with Lafolè, Topazio and Nereide, was to form a barrier off Sollum. The four submarines were positioned within twenty miles of each other, starting from a point 30 miles by 30° from Ras Azzaz (Diamante, in particular, positioned itself 40-50 miles by 030° from Ras Azzaz), to defend the ports of Cyrenaica and, if possible, attack enemy ships sailing between Malta and Alexandria in Egypt.

At 00.20 on 10 June, Lafolè spotted Diamante and noticed it slowing down, perhaps caught by a breakdown. Its failure to return then made it impossible to verify whether there had actually been a breakdown, and the same goes for another mysterious episode that took place that day: at 09.45 PM on June 10th, the British destroyer H.M.S. Decoy sighted a submarine that had emerged only 275 meters away and maneuvered to ram it, but the turn turned out to be too wide and late and the bow of the destroyer missed the conning tower of the submarine by about thirty meters. The submarine then began to dive astern, and H.M.S. Decoy fired a 101 mm round at it with the “B” gun.

However, the very short distance (about 90 meters) meant that the shot “flew over” the submarine harmlessly, frustrating the use of artillery that could not be lowered enough to hit it. At this point the destroyer dropped a depth charge, then launched a rocket to mark the spot where the submarine submerged, and finally launched a “package” of four depth charges. The crew of H.M.S. Decoy smelled a strong smell of naphtha and sighed a two-mile-long fuel slick.

No Italian submarine reported being attacked at a time and place compatible with those of the H.M.S. Decoy’s action, while the position indicated by the latter was very close to the ambush sector assigned to Diamante. It is therefore very likely that this was the submarine encountered by the British ship. If this was the case, it is likely that H.M.S. Decoy’s depth charges did not cause any significant damage, since he continued his mission regularly.

On June13th, Diamante received orders from Maricosom to move to waters closer to Tobruk, more precisely 35 miles by 025° (or 030°) from that city. Another six days passed without any noteworthy events, and at 07:35 PM on June 19th Maricosom informed the boat of the sighting of an enemy submarine off Tobruk. Finally, at 10:25 AM on June 20th, Diamante received orders to return immediately to Tobruk, sailing on the surface. In this last communication with the base Diamante reported that it would reach Sidi Abeiba (23°45′ E), about 15 miles west of Tobruk, and a unit of the I Destroyer Squadron was sent to meet the boat. However, it would never make it to the appointment.

While sailing to Tobruk, Diamante was sighted by British forces, and at midnight on June 19th – shortly after the sighting – its presence was communicated by radio to the British submarine H.M.S. Parthian, which, under the command of Lieutenant Commander Michael Gordon Rimington, which was on patrol off the coast of Cyrenaica. (For another version, H.M.S. Parthian was informed of the imminent arrival in Tobruk of Italian submarines on the basis of an interception by the Government Code & Cypher School of Bletchley Park, better known as “Ultra”, which had deciphered an Italian message giving instructions for the return to Tobruk of the Lafolè and another submarine whose name was not mentioned, i.e. Diamante). Immediately H.M.S. Parthian, which was moving farther west, reversed course, and moved to 32°35′ N and 24°10′ E (30 miles north of Tobruk), and then dove before dawn and waited for hours, in silent trim.

At 01:00 PM (according to another source at 2:45 PM) on June 20th, H.M.S. Parthian’s watchman, lying in wait off Tobruk, sighted Diamante (“a long, low object” shortly afterwards identified as a Perla-class submarine) coming unknowingly toward the submarine from a distance of 5,940 meters. Rushing to the launch chamber, Rimington had the presence of the boat confirmed with the use of sonar, then, after making sure that there were no other submarines in the vicinity, he ordered the combat station. H.M.S. Parthian opened launch tubes 1, 2, 3 and 4, distance and bearing were communicated to the person in charge of the launch station, the periscope was lowered, and the submarine descended to a depth of twenty meters, approaching the unsuspecting Diamante at full speed. Then H.M.S. Parthian slowed down and returned to periscope depth, while the Italian submarine passed it forward facing the starboard side, only 400 yards away, as Rimington had calculated. The tubes were prepared, the new data confirmed by the launch station, and H.M.S. Parthian launched four torpedoes spaced three seconds apart, from a distance of just over 350 meters. It was 3:02 PM.

H.M.S. Parthian was lost in the Mediterranean Sea between July 28th and August 11th, 1943

After the allotted time, the crew of H.M.S. Parthian, which had descended to greater depth after the launch, heard four explosions, also at intervals of three seconds: all four torpedoes had hit Diamante , which immediately sank with the entire crew at 32°35′ N and 24°10′ E (for another source 34°42′ N and 23°49′ E or 32°41’30” N and 23°49′ E),  about thirty miles north of Tobruk (for another source, about 35 miles north-northwest of that city). From aboard H.M.S. Parthian, after the explosions of the torpedoes, a fifth, deafening final explosion was also heard, more violent than the others: the epitaph of the submarine and its crew. British sources claim that Diamante “disintegrated”.

The British boat, after checking with the periscope that the horizon was clear, resurfaced, and two men, Chief First-Class Charles Graham Ascomb and Signalman Bush, climbed into the conning tower and searched the surrounding waters, in an attempt to locate any survivors: but in vain. Lines were prepared to be thrown to the castaways, but they were of no use. No one was saved. Commander Parla, four other officers and 38 non-commissioned officers and sailors perished aboard Diamante.

H.M.S. Parthian, diving again and moving away, resurfaced late at night and radioed the success to the base in Alexandria, Egypt. When the boat returned to base, it was Admiral Andrew Browne Cunningham himself, the commander of the Mediterranean Fleet, who went to congratulate the crew of H.M.S. Parthian on the first success of the British submarine in the Mediterranean. Commander Rimington would be decorated with the Distinguished Service Order for sinking Diamante, while another member of the Parthian’s crew, chief petty officer Robert John Backhouse, received the Distinguished Service Medal at Buckingham Palace on February 24th, 1942. Other H.M.S. Parthian men were also decorated for the action; the entire crew was awarded the “Gallantry Award”, as reported in the “London Gazette” of September 11th, 1940.

Diamante was the first of hundreds of casualties claimed by British submarines in the Mediterranean. It was the third in the very long line of Italian submarines that would sink during the war: the second in the Mediterranean.

The elementary school named after Lieutenant Perla in Licata (Sicily)

The unfortunate commander Parla was awarded a Bronze Medal of Military Valor in his memory. He left behind his mother in Licata and a fiancée in Tuscany. In Licata, in the church of Sant’Angelo, a plaque with a bust commemorates the sacrifice of Commander Parla. An elementary school in the village was named in his memory. After so many years, an elderly woman from Licata still throws flowers into the sea every morning of June 20th, from the arm of the statue of the Heart of Jesus, on the eastern pier of the port, in memory of Angelo Parla and his men.

Original Italian text by Lorenzo Colombo adapted and translated by Cristiano D’Adamo

Operational Records

TypePatrols (Med.)Patrols (Other)NM SurfaceNM Sub.Days at SeaNM/DayAverage Speed
Submarine – Coastal170030011 90.91 3.79



Crew Members Lost

Last NameFirst NameRankItalian RankDate
AccattinoLorenzoNaval RatingComune6/20/1940
BarelliFrancescoNaval RatingComune6/20/1940
BasiliottiGiuseppeSublieutenantSottotenente di Vascello6/20/1940
BrigantiFrancescoNaval RatingComune6/20/1940
CabiancaGuerrinoNaval RatingComune6/20/1940
CarenaPaoloNaval RatingComune6/20/1940
CoppolaFrancescoNaval RatingComune6/20/1940
D’antonioGiuseppeNaval RatingComune6/20/1940
De RobertisNicolaNaval RatingComune6/20/1940
Di FrancescoAmerigoChief 2nd ClassCapo di 2a Classe6/20/1940
ErcolesEugenioNaval RatingComune6/20/1940
FabbroParideNaval RatingComune6/20/1940
FagioliNedoNaval RatingComune6/20/1940
FerrariRomoloChief 2nd ClassCapo di 2a Classe6/20/1940
FerraroGaetanoNaval RatingComune6/20/1940
IngargiolaGianbattistaNaval RatingComune6/20/1940
LironiElvezioJunior ChiefSottocapo6/20/1940
MarinoUgoNaval RatingComune6/20/1940
ModicaAntoninoChief 3rd ClassCapo di 3a Classe6/20/1940
MontanariAntonioChief 2nd ClassCapo di 2a Classe6/20/1940
NicolaiDanteNaval RatingComune6/20/1940
PacittoBiagioJunior ChiefSottocapo6/20/1940
ParlaAngeloLieutenantTenente di Vascello6/20/1940
PetrilloCosimoJunior ChiefSottocapo6/20/1940
PingueAzeglioSublieutenant G.N.Tenente G.N.6/20/1940
RastrelliRomoloNaval RatingComune6/20/1940
RivelliEnricoChief 3rd ClassCapo di 3a Classe6/20/1940
RonchiClaudioJunior ChiefSottocapo6/20/1940
SagaceAntonioChief 2nd ClassCapo di 2a Classe6/20/1940
ScarpaOlintoNaval RatingComune6/20/1940
SchedanPolicarpoJunior ChiefSottocapo6/20/1940
SigariGiuseppeJunior ChiefSottocapo6/20/1940
SimonelliLuigiNaval RatingComune6/20/1940
SiracusaFrancescoJunior ChiefSottocapo6/20/1940
SpazianiSilvanoNaval RatingComune6/20/1940
ToniEzioChief 2nd ClassCapo di 2a Classe6/20/1940
TrovatoSalvatoreNaval RatingComune6/20/1940
UccelliCarloSublieutenantSottotenente di Vascello6/20/1940
ValerioGiuseppeJunior ChiefSottocapo6/20/1940
VigoPompilioJunior ChiefSottocapo6/20/1940