Background

At the start of the war, the Regia Marina had some successes in anti-submarine warfare, but overall did not perform well, for reasons related to organization, tactics and technology. By the middle of 1941 this had turned into a serious headache with losses on the North Africa route mounting. From September 1941 onwards, steps were taken to address the shortcomings.

Technology Transfer

In autumn 1941 the German navy had started to equip Italian escort vessels withASDIC active sonar equipment (S-Geraet) and depth charge launchers (WBW).  The priority was apparently given to equipping escort units in the Aegean, where allied submarines had been active and successful for a while.  In December 1941, the Kriegsmarine established a sub-hunting flotilla at Piraeus to be able to contribute to the Regia Marina’s effort. 

Italian vessels were equipped with the German sonar when they went into wharf in Italy for general maintenance, i.e. they were not pulled from service to have this equipment fitted. My guess is they were stretched so thin already that this would not have been possible.  Until the German sonar came along, the Italian vessels had to use passive listening devices to locate submarines.  One is tempted to conclude from the significant successes achieved by Allied submarines that these were not very good at fulfilling their purpose.

The sonar equipment on the Italian vessels was operated initially by German sailors, while Italian naval personnel was attending the Kriegsmarine anti-submarine school at Gotenhafen. One of the first Italian units to be outfitted with the German equipment was the older destroyer Alvise da Mosto. She was sunk in a surface engagement with the Royal Navy’s Force K from Malta on 1 December 1941, off Tripoli (see this older entry). It had only been outfitted at the Italian navy shipyard in Fiume two weeks beforehand, it appears.

Alvise da Mosto underway in the first months of the war, probably off Taranto. USMM.

Report for the Kriegsmarine

A report by the two surviving German sonar operators found its way into the files of the German naval command, and is preserved at NARA.  Both of these men were re-assigned to other Italian escort vessels and when on the Spica-class torpedo boat helped sink HM Submarine Tempest on 13 February 1942 (this article describes the incident). In this attack, Ordinary Seaman Maidenoff being credited with re-establishing her location when she was submerged.

The report must be from after March 1942, since it refers to the death of Commander del Anno who was lost when his destroyer went down in a gale  at the 2nd battle of Sirte. While probably not a completely accurate report, it is an interesting eye-witness statement. Below is a translation of the report.

Report about the Actions of the Destroyer “Da Mosto” from 18 November 1941 to 1 December 1941 based on the Statements of the two Rescuees Petty Officer Rublack and Ordinary Seaman Maidenoff

 

German listening crew consisting of:

Petty Officer (Bootsmaat) Rublack

Able Seaman (Matrosengefreiter) Hartmann

Able Seaman Macar

Ordinary Seaman (Matrose) Maidenoff

Ordinary Seaman Retter

During the move from Fiume to Pola on 18 November a submerged Italian submarine located at 4200 [metres].  Echo remained good until the end. Speed 16 knots.

During the move Pola -Tarent on 24 November one steamer escorted. Defect on the motor cinema [screen of the sonar, I guess]. Mirror running too slow, therefore no correct distance.  Reason: strong variations in net. Turning the unit off leads to only slight improvement.

Around 0700 [hours] perfect echo ranged at 320 degrees. Distance could not be fixed. Boat [this refers to Da Mosto] zig-zags at high speed, steamer turns away.  This location was very probably an enemy submarine since a few hours later  an attack occured on another steamer in the same area (statement by the commander).

Enter Taranto on 25 November around 1500. With help from a German mechanic the cinema motor is changed against another one from the installation of another boat.  The work is completed shortly before the boat leaves harbour.

On 26 November 1500 left harbour with a tanker for Trapani.  In the Messina Straits submarine alarm raised by another boat. Search by Da Mosto without result.

At the southern tip of Sicily an unknown mine barrier was well located.  Proceeded according to guidance by S-Geraet.

28 November at 2000 entered Trapani with tanker.

30 November at 0300 left harbour with tanker on western route to Tripoli.  On the way location of a floating mine, a buoy, and a wreck.  Furthermore three French coastal vessels were located on 3,600 to 3,800 metres, which were only then recognised from the bridge.

During the course of 1 December attacks by English bombers occured in several waves. The tanker was hit in the stern and remained motionless. Attempts to take it in tow failed.  Air defense of tanker was weak.  Around 1730 English surface units came into view.  Da Mosto immediately went into the attack and achieved hits on a cruiser.[1]  After a short time Da Mosto was hit in the stern.  Ammunition and the Italian depth charges went off.  During the sinking the forward torpedoes were fired, but without a hit. Da Mosto sank around 1800. The crew gave cheers to its ship, the Duce and the Führer.  The English destroyers drove through the swimming crew without attempting to rescue someone, and shouted derisively “Good bye boys”.

Petty Officer Rublack swam to the tanker with two Italians to bring a still intact boat into the water and to sink the tanker. A destroyer opened fire however, so that the intent could not be carried out.  The tanker then also sank soon afterwards.  Another destroyer appears to have had the intent before that to take it into tow[2].

The S-Geraet was kept manned until the start of the engagement when the boat went to high speed.  The listening crews thereafter went to their battle stations on the guns.  Petty Officer Rublack and Ordinary Seaman Maidenoff were on the bridge. Able Seaman Macher fell at the rear gun.  Nothing has been observed concerning the whereabouts of Able Seaman Hartmann and Ordinary Seaman Retter, who until the last moment manned the S-Geraet.

Around 2300 the torpedo boat Prestinari reached the site of the engagement and took the survivors on board.

The commander, Fregattenkapitaen (Commander) del Anno was very complimentary about the performance and the brave behaviour of the German listening crew. Petty Officer Rublack received the Iron Cross 2nd Class and the Italian Bronze Medal of Valour, and Ordinary Seaman Maidenoff the Iron Cross 2nd Class and the Italian War Merit Cross. The commander received the Gold Medal (later killed in action as commander of Scirocco).

Alvise da Mosto underway in the 1930s. The picture shows the unusual configuration of the B-turret very well. USMM via Wikipedia.

 

 

Notes

[1]This is not correct.

[2]This is wrong.

Further Reading

Part 2 of the Series

Part 3 of the Series

Loss of HM Submarine P.38 

Loss of HM Submarine Tempest

A very informative article on the anti-submarine warfare development of the Kriegsmarine can be found at this link (search the document for “magnetostrictive” to jump directly to the ASW section).

A very informative, but highly technical, article on German passive sonar can be found at this link.