History of the Italian plans to transform motorships into military units for war in the oceans from 1940 to 1943
After Italy’s foray into WW II (June 10th, 1940), Supermarina began a series of studies with the purpose of transforming a certain number of motor vessels of medium displacement, but with large range, into units modified to intercept and destroy British maritime traffic in the oceans.
These studies, which were considered part of a single project, did not produce any practical result since during the favorable first year of war, Italy failed, as we know, to seize the British bases of Suez and Gibraltar, which precluded the existence of Axis surface ships from the Mediterranean into the oceans.
However, since Italy had a certain number of hulls fit for this use and already placed outside the Mare Nostrum (the Italian and German merchant ships docked in neutral or friendly ports, such as the Japanese ones, were quite a few), the supreme command of the Italian Navy, even though with a great delay, decided in the summer of 1940 to begin a study. This study attempted to emulate the orders given by the Kriegsmarine relative to the creation and utilization of the so-called “auxiliary cruisers.” It should be noted that since 1939 Germany had created the first “raiders”, introducing them, since early 1940, into the oceanic trade routes.
On the 6th of September, 1940, the Project Office of the “Stato Maggiore” of the Navy generated a first list of three modern cargo ships, all belonging to the “Monginevro” class, (at the time, near completion at the “Cantieri Riuniti dell’Adriatico” shipyard) and all fit for radical transformations. The three ships belonged to the Società di Navigazione Alta Italia and were in an advanced phase of completion (the first one was 99% complete, the second one 96% and the third one 92%). These ships had all the required characteristics for long missions (obviously after a few alterations), and, due to their structural characteristics, could easily receive the installation of the necessary guns, torpedo launchers, antiaircraft guns, and the equipment and the extra storage indispensable to a raider of the oceans.
The units of the Moginevro class were 124 meters long, 18 meters wide and had a drought of 7.40 meters loaded. The total displacement was around 5,500 tons with a capacity of 8,600 tons. The three ships could reach a maximum speed of 16.5 knots (and maintain 15), and had a range, at a speed of 15 knots, of 12,000 miles.
The engineers of the Regia Marina in charge of compiling a report on the characteristics of the hull under construction reported: “the deck is wide, quite unobstructed and it is quite suited for the installation of guns and mines… the silhouette of the “Monginevro” make us believe they will be seaworthy. The deck is wide and well-equipped, the quarters and stowage comfortable and in large quantity…” So, after a first analysis, Supermarina took positive, though incomplete, estimates and made assumptions (since the ships were not ready, they could not be actually tested) on the potentiality of these ships, moving on to an actual implementation plan to make them ready for combat.
It was thought to arm the ships in a manner similar to the one implemented by the German navy for the raiders. The naval engineers of Supermarina introduced the idea of installing six 152/40 guns (one near the bow, one near the stern, and four to the sides), two antiaircraft and anti-ship 37mm guns (on the boat deck, past the funnel), two 20mm AA guns (on the boat deck, or on top of the deck, near the compass), two 450 mm torpedo launchers (one on each side, installed in the hull about 5.5 m below the water line), and a smoke screen apparatus.
The selection of the 152 mm guns (weapons with a maximum range of 16,000 meters) was dictated by the need for a weapon of assured destructive capabilities against the hulls of merchantmen, and also for the need to respond to the guns of British light cruisers equipped with similar weapons. The 120 mm guns with which were equipped some Italian destroyers, at the time, and some auxiliary vessels (including the auxiliary ship Eritrea which operated in the Red Sea and the Indian Ocean), were not selected, at least initially, because they were thought insufficient in facing large enemy cargo ships often equipped with 114mm, 120mm and even 152mm guns, or the British light cruiser of the Leander class often utilized to patrol oceanic routes.
To allow the Monginevro to locate their prey over the horizon with greater speed and ease, it was thought to install a hydroplane with folding wings, but this idea was later abandoned due to technical problems (boarding a plane would have required the creation of a gasoline bunker and other accessories which were expensive and voluminous). Regarding the offensive weaponry aboard, it was decided to equip the ships with 200 rounds and 5 star-shells for each 152 mm barrel, 300 shells for each 37mm guns and 6,000 cartridges for each 20 machine gun. In addition, over 600 explosive charges were to be placed inside the hull and the quick-work (the upper part of the ship extending from the hull) to provide for self-destruction in case of capture or severe damage.
The engineers of the Regia Marina in charge of the conversion of the “Monginevro” did not forget to plan for the installation of about 100 to 150 mines, of the Elia type, stowed in the stern hold. These mines would be lifted by cranes and transferred on specially constructed rails. The radio and signaling equipment would have consisted of the already existing radio equipment (a D/F fix, a 0.5 Kw transmitter, and a short and medium wave receiver). In addition, it was planned to install two additional receivers and a small radio.
Above the fore-bridge there was enough space for a model 60 or a model 90 discovery searchlight, possibly retractable, a signaling light projector, and an echo-sounding gear. The Monginevro’s fuel consumption was excellent (with a normal load of 770 t. they could cover over 12,000 miles at fast speed), but was not good enough for the Italian Navy engineers who wanted to increase the already excellent range by almost four fold, striving for a maximum range of 40,000 miles, or the equivalent of 5 months without calls. The plan called for the installation of an additional bunker for an additional 1,730 t. of oil fuel (for marine diesel engines).
The new bunker would have been installed on the hold’s dunnage, and in the forward and aft peak. Also, the Monginevros would have received large storage areas for flour and foodstuff, a refrigerated area, two ovens for the baking of bread, plus a large infirmary with a large selection of medicines. Also, to guarantee the good health of the personnel, one of the forward holds would have hosted a stable for a dozen milk cows and a large cage for about 50 chickens. Finally, the equipment for the new Italian “pirates” would have included a repair shop and spare parts depot.
The crews of the Monginevros would have included 12 officers, 10 petty officers, 14 sailors and mechanics, 42 sailors to man the guns, plus, if needed, 18 additional officers and sailors as crew for captured ships. Technical difficulties, politics, and financial issues did not allow Supermarina to go beyond a simple but highly detailed study for the transformation of the Monginevro, the Monviso and the Monreale. As it is known, the Italian Navy, since the very beginning of the war, had to concentrate all efforts on resolving multiple high-priority emergencies, since it had to face the toughness of the British Navy and Air Force.
During 1942, also considering the United States’ entry into the war, the project for the conversion of the Monginevros into raiders was definitively abandoned, leaving to the surviving German “Handels-Stor-Kreuzer” (cruisers for the disturbance of maritime traffic) the task of spreading panic along the oceanic routes.
Note:
Between 1940 and 1943, the Kriegsmarine successfully deploy several raiders on all oceans: Orion (10 ships sunk, including 2 in collaboration with Komet), Atlantis (22 ships sunk), Widder (10 ships sunk), Thor (22 ships sunk), Pinguin (32 ships sunk), Stier (4 ships sunk), Komet (6 ships sunk), Kormoran (11 ships sunk plus the Australian cruiser Sydney), Michel (17 ships sunk).
Atlantis was sunk by the British cruiser Devonshire in the Southern Atlantic Ocean (11/22/1941). Thor exploded following a fire in Yokohama (11/30/1942). Pinguin was sunk near the Seychelles by the British cruiser Cornwall. Stier sunk after a fight with the American armed ship Stephen Hopkins (9/27/1942). Komet was sunk near Cap the Hague by the British VAS N 236 (10/14/1942). Kormoran sunk after a fight with the Australian cruiser Sydney west of Sharksbay (11/19/41). Michal was sunk by the US submarine Tarpon near Yokohama (10/17/1943)