The breakwater viaduct prior to the attack (above), with one span collapsed immediately after the attack (below) and with the collapsed span of the viaduct removed.

The Grand Harbour breakwater was the main target of an attack by Italian motor torpedo boats on July 26, 1941, by the Decima Flottiglia Mezzi d’Assalto (MAS), the 10th Assault Vehicle Flotilla, a commando frogmen unit of the Regia Marina (Italian Royal Navy) created during the Fascist regime.

The attack actually took place on July 26, but as the operation took part during the night between the 25th and 26th, the official British records refer to the 25th as the date of the attack. A similar mission was to have taken place a month before on June 26, but was cancelled due to bad weather.

The Italians’ capabilities for such missions were known, though some of their missions had failed, such as the ones on Gibraltar, Algiers and Alexandra.

The plan was to remove any blockage under the viaduct on the St Elmo side of the breakwater to make way for motor torpedo boats (MTBs) or motoscafi da turismo (MTs) to attack and destroy naval units in the Grand Harbour and also damage submarines in Marsamxett harbour.

The vessels that took part in the mission included the 1,568-ton RN Diana, a fast torpedo-boat carrier launched on May 20, 1940, two motoscafi armato silurante (MAS) with a crew of eight or nine each, a motoscafo turismo lento (MTL) with a crew of six that carried two manned, slow-running, manned torpedoes called SLC (siluri a lenta corsa) and nicknamed Maile by the Italians; nine MTs with a one-man crew and two SLCs with a detachable explosive bow and a two-man crew that were carried in the MTL.

The plan was that RN Diana, which was carrying nine MTBs, a hoisted MT, an MTL in tow and two MAS in company, were to leave Augusta at 6.15am on Day 1 (July 25) and proceed at 22 knots by inshore route round Capo Passero and thence to a position 66° N, 14° 35’ E. On reaching this position, Diana and all the other ships were to stop and disembark its MTBs and MTs and launch the hoisted MTL. Diana was then to retire to a position 36° 21’ N, 14° 40’ E and remain between that position and Cape Passero, acting as a cover to MAS until ordered to return by the senior officer of the MAS. If by 10am on Day 2 (July 26) no orders would have been received, the ship had to return to Augusta.

On parting company from the Diana, both MAS (one having an MTL in tow) the MTs and the nine MTB were to proceed on auxiliary motors to a position 044°, 3.5 miles from Fort St Elmo where all the ships were to stop and the MTL launched.

The MTL was to then proceed immediately to the edge of Dragut shoal where it had to disembark its two SLCs. The first SLC had to proceed to attack the St Elmo viaduct, which was timed to take place at 4.30am on July 26. The second SLC was to attack submarines in Marsamxett harbour.

At the same time that these attacks were supposed to take place, the nine MTs and MTLs were to take up a waiting position on the edge of Dragut shoal. As soon as SLC would have made the breach, the MTs would have followed the MTS into the Grand Harbour. In the event of the gap made by the SLC being insufficiently large, the MTs were to force their way through.

The last thing that the Italians expected was that Malta’s defence was backed up with British radars

Inside the port, the MTs were to attack targets that had been previously arranged, based on the Italians’ latest photographic reconnaissance, which later proved to be outdated by at least three days.

In the meantime, both MAS were to sail in a straight line from Pozzallo to St Elmo at 3am on July 26, where they were to stop at 4.35am and then proceed in an 018° direction on auxiliary motors until 5.35am. The MTL was expected to have recovered the personnel of the first SLC, which should have overtaken the MAS boats.

Two types of Italian motor torpedo boats that were used during the attack.

Personnel were then to be transferred to MAS boats and the MTL would be taken in tow. At 5.35am, both MAS would proceed on main motors at 15 knots when they would have been joined by the MTs, which would have picked up the crew of the second SLC and also the pilots of the MTs after forcing the entrance to the Grand Harbour.

The MAS would then proceed on course 018° at 25 knots. If the above meetings do not take place all ships were to maintain the same course at maximum speed until they reach the Sicilian coast near Pozzallo. If the MTS would meet the MTL before personnel would have been transferred to the MAS, it was to take them on board and then sink the MTL. If contact with MTS and MTL was not made by 8am on July 26, the MAS were to return to Augusta via the coastal route.

Additional special orders dated July 25 stipulated that no lights were to be used except for certain pre-arranged signals. This night cruising order was to be taken up without signal at 9pm on July 25.

The Diana was to signal the time it would be have stopped in position, and in the event of sighting the enemy, by day use normal procedure (whatever that was), and by night it were given a series of light signals procedures they had to follow.

The MT pilots had a set of 10 detailed orders they had to follow; they were given details on how to manoeuvre into and inside the harbour and to steer away from any obstructions and unforeseen obstacles.

If any MT got lost it was to remained stationary and roar its engines three times every five minutes.

One of the slow-running manned torpe doe s called SLC (siluri a lenta corsa), nicknamed Il Miale. Photo: Vincent P. O’Hara, Enrico Cernuschi

If by dawn the MTs had not been picked up, they were to proceed north until reaching Sicily. They could have been ordered to attack the enemy at any moment. If the group was heard, sighted or illuminated and fired upon they were to turn back at full speed and wait till dawn.

If, however, they were caught in the beam of the searchlight but not fired on, they were to reduce speed to a minimum.

However, the Diana was detected by the Air Ministry Experimental Station (AMES) No 504, the low-level coverage radar at Dingli, before midnight on July 25, and later on, the full operation was followed by No 502 at Madliena and No 501 at Tas-Silġ, which were continuously updating the War Room at St John’s Cavalier, and the coastal defence batteries mainly manned by Maltese soldiers were waiting eagerly for their prey. The last thing that the Italians expected was that Malta’s defence was backed up with British radars. In their planning they had thought of risks coming from naval ships and submarines, land searchlights and sound detectors, but radar detection was never mentioned or even contemplated.

Vittorio Moccagatta, who was in command of and believed to be killed in the operation.

How the Italian operation was observed and followed from Malta?

At 8.55pm on July 25, No 504 radar at Dingli detected a surface plot south of Sicily approaching Malta.

The War Room was alerted, which in turn alerted various listening outposts along the northerneast coastline.

From 10pm onwards the noise of the motor boat engines were heard at various points along the northeast coast of Malta but too far out to sea to warrant exposing the searchlight systems (DELs).

No suitable naval ships were available to send out to engage them.

By 11pm the plot had approached to within 14 miles of Malta and all guns were manned and the air raid warning sounded. At this time, the plot altered course and approached more slowly. A striking force composed of Swordfish planes was prepared as rapidly as possible but they could not be ready until 11.55pm.

At 11.25pm St Elmo light was switched on for five minutes as it was thought that the enemy had been disappointed in finding a convoy not leaving and it was hoped this ruse might be reported by the MAS boats – which could still be heard – and attract the cruiser within range of the guns. After taking off at 11.55pm the Swordfish unfortunately split up and eventually turned back without sighting the Italians.

There seems to be no reason to believe that a single boat escaped back to Sicily. About 15 boats were destroyed, and three captured

At 1.30am a motor boat was heard closing in on Grand Harbour and he DELs were switched on. However, nothing at sea was spotted but the boat withdrew.

At 4.46am the ‘all clear’ was sounded but one minute later a track was seen approaching St Elmo and a wake was seen by a look-out at Tigné.

A few seconds later an explosion blew up the breakwater viaduct, one span of which collapsed. At the same time the searchlights were illuminated and the coastal defence batteries nearby opened fire. For the next few minutes the illuminated area just off the harbour entrance was crisscrossed by tracer bullets fired from every close range weapon that was available.

The remains of the central legs that used to support the viaduct linking St Elmo Point to the breakwater. In 2012 a new bridge was built linking the span.

Many of the Italian vessels were hit and blew up and after a few minutes the firing ceased as there appeared to be nothing left to fire upon. The attack had been utterly broken.

At 5.30am when dawn had broken, two objects which had been thought to be wrecks were seen moving and fire was reopened on them. Within a few minutes both had sunk and exploded under water. By this time cannon Hurricanes were in the air and were gunning any retreating boats that could be discovered.

It was difficult to say which boats fell to the shore defences and which to the air attacks, but there seems to be no reason to believe that a single boat escaped back to Sicily. About 15 boats were destroyed, and three captured.

The shore defences disabled one MTL 36 miles from Malta (which was probably was sunk by the Italians at the same time as a hospital ship removed the dead), one MTS and five to six MTs.

Hurricanes destroyed two MAS and two to three MTs. One SLC was destroyed in the explosion during the attack on the viaduct and the other SLC ran aground.

One MAS and an MT were captured and towed in and another SLC was found partly under water and partly damaged.

The MAS were No 451 with Sub Lieutenant Scioletti Giorgio in command and No 452 with Capitano di Fregata, Vittorio Moccagatta, who was in command of the whole operation, who was believed to be killed together with Lieutenant Parodi in command of an MAS also believed killed, together with Medical Captain Bruno Falcomata. They had a crew of 12, of whom none were captured, six buried at sea, four believed to have embarked on a rubber boat with their fate unknown and the fate of the remainder was unknown.

Four officers, 14 ratings and two pilots were taken prisoners of war. They were all interrogated, while some of them were hospitalised.

All of them except one were young and single, young and very well trained not to give any information during the interrogations, other than their personal details.

In his report to the Lords Commissioners of the Admiralty, the Vice Admiral, Malta remarked that: “The harbour defences of Malta, largely manned by Maltese, scored an outstanding success in this, their first action, and to them must go the entire credit for maintaining the security of the harbour.

“The very accurate RDF (radar) plot which allowed us to follow exactly the movements of Diana, has given us the utmost confidence that we shall be very advantageously placed should a seaborne invasion come”.

The breakwater

The invitation to tender for the construction of the Grand Harbour break­water project was issued on October 8, 1902, by Corderoy, Selby & Corderoy Surveyors of 21, Queen Anne’s Gate, Westminster, London, on the instructions of the Director of Works.

The contract, worth £476,327.6s.3p, was awar­ded to S. Pearson & Son Ltd of 10, Victoria Street, London, as per its quotation, dated December 9, 1902.

From official records it appears that there was only this offer. The work was to be completed in six years.

The quote also included an option of an additional five per cent in the cost of the St Elmo side, if the work would be completed in four and a half years.

RN Diana and HMS Thrasher

The Diana (top), launched on May 20, 1940, was sunk north of Tobruk, Libya, on June 29, 1942, when it was hit by four torpedoes fired by HMS Thrasher. A total of 336 men perished in the sinking, and 119 were rescued.

Major Tony Abela is a former RAF telecommunications technician and author of Malta’s Early Warning Systems during World War II. He is also honorary secretary of RAFA Malta GC and chairman of Malta Air Traffic Services.