An Italian CB-class submarine
Although the presence of midget submarines on both sides was
rumoured during the Russo-Japanese War, the Italian Navy may claim to have been
the first to deploy midgets in 20th-century warfare. During World War I, a few
small submersibles of c.16 tons (16.25 tonnes) surfaced displacement were
constructed and, having proved unsuitable for operations outside sheltered waters,
were used for harbour defence in the Adriatic. These pioneer designs were
dusted off in the mid-1930s when, at the time of Mussolini’s venture into
Abyssinia (now Ethiopia), conflict with Great Britain temporarily threatened. A
weapon for clandestine penetration of such British Mediterranean bases as
Malta, Gibraltar and Alexandria was advocated by many Italian officers, with
Cdr Angelo Belloni, a leading spirit in the training of volunteers for the
Decima Flottiglia MAS (10th Light Flotilla), the Italian Navy’s “special attack
weapons” unit, prominent among them.
In the event, the Maiale (“Pig”) manned-torpedo was to be
the major penetration weapon; but in the pre-war years it was planned that
midget submarines should penetrate enemy bases, either to carry out torpedo
attacks or to release frogmen to place explosive charges. In conditions of
strict secrecy, the Italian Navy constructed and had operational by April 1938
the midget submarines C.A.1 and C.A.2 (C=Costiero-tipo, “coastal-type”), built
by Caproni, Taliedo of Milan.
In their original form, C.A.1 and C.A.2 were two-man boats
displacing 13.5 tons (13.7 tonnes) surfaced; 32.8ft (10m) long overall; 6.43ft
(1.96m) in beam; and drawing 5.25ft (1.6m). On the surface, a single-shaft 60hp
MAN diesel gave a maximum speed of 6.5kt (7.5mph, 12kmh) and a range of 700nm
(805 miles, 1295km) at 4kt (4.6mph, 7.4kmh). Submerged, a 25hp Marelli electric
motor gave a maximum 5kt (5.75mph, 9.25kmh) and a range of 57nm (65.5 miles,
105km) at 3kt (3.45mph, 5.5kmh). Armament consisted of two 17.7in (450mm)
torpedoes in external dropping gear.
Trials soon showed that C.A.1 and C.A.2 were not capable of
operations involving sea passages of any distance. Nor was there much chance of
the midgets surviving independent missions in the clear, shallow, inshore
waters of the aircraft-dominated Mediterranean. In 1941, it was decided that
the midgets must be carried to their target areas on mother boats and released
under cover of darkness to penetrate defended anchorages and lay explosive
charges. The diesel units were removed from both midgets, as were the torpedo
racks. This reduced displacement to 12 tons (12.2 tonnes) surfaced and 14 tons
(14.2 tonnes) submerged; increased maximum submerged speed to 6kt (6.9mph, 11kmh)
and submerged range to 70nm (80.5 miles, 129km) at 2kt (2.3mph, 3.7kmh); and
permitted a crew of three to be carried; at least one a trained “frogman”.
The Leonardo da Vinci with the CA seated in the special cradle.
Date: December 1943
Place: Hudson River,
New York, USA
Attack by: Italian
midget submarine “C.A.2”
Target: Shipping at
anchor and dock installations
Urged on by the German high command, who stressed the moral
effect on the Allies of increased Italian naval effort in the Atlantic, Cdr
Prince Junio Valerio Borghese, commanding the 10th Light Flotilla, planned
spectacular and potentially suicidal missions for the Italian midgets: attacks
on the British base at Freetown, Sierra Leone, on the west coast of Africa –
and on harbours along the east coast of the United States. The Freetown plan,
for which C.A.1 was allocated, was abandoned when it was decided that British
defensive measures allowed no chance of success; but the operation against the
USA, with New York specified as the target for maximum psychological effect,
reached an advanced planning stage.
In mid-1942, in preparation for the New York raid, C.A.2 was
transported overland to Bordeaux, where “Betasom”, headquarters for Italian
submarines operating in the Atlantic, was commanded by Capt Enzo Grossi. There,
too, came the Marconi-class submarine Leonardo da Vinci of 1,190/1,489 tons
(1209/1513 tonnes), selected as the midget’s carrier. Under the direction of
Cdr Borghese and SubLt Massano, Italian workshops at Bordeaux under Major
(naval rank) Fenu removed Da Vinci’s 3.9in (100mm) gun and in its place, just
forward of the conning-tower, constructed a semi-recessed “pouch” with
retaining shackles for C.A.2. This arrangement led to the mother boat being
designated the Canguro (“Kangaroo”). Sea trials under Borghese’s command proved
to his satisfaction that the midget could be launched from the submerged
Kangaroo and could be recovered when the mother boat surfaced beneath it. The
latter point was important in avoiding any indication that the projected
mission was regarded as suicidal: just so had the IJN made “official” plans to
recover its midgets after Pearl Harbor.
According to Borghese, the Kangaroo (not Da Vinci, which was
sunk by British warships off the Azores in May 1943) would launch its midget
while submerged off New York Bay. C.A.2 (or, in the later stages of the
operational planning, the near-identical C.A.3 or C.A.4) would make its way by
night into the crowded harbour at the mouth of the Hudson. Two of the three
crewmen, in frogmen’s gear, would leave the boat to plant time-fuzed explosive
charges – eight 220lb (100kg) charges and twenty 4.4lb (2kg) “limpets” were
carried – under ships and against dock installations. Then C.A.2 would slip
downriver to make rendezvous at sea with the Kangaroo.
The suicidal nature of the plan is obvious. Borghese made
the airy assumption that New York’s harbour defences “against such a surprise
attack presumably didn’t exist” – although the “happy time” enjoyed by German
U-boats off the American east coast in the earlier part of 1942 had resulted in
much-improved anti- submarine patrolling. The Kangaroo would have to surface in
American coastal waters to allow the midget’s crew to enter their craft, since
they had no means of access from the mother boat; and it would have to surface
again offshore, in the aftermath of the attack, to retrieve the midget.
Finally, it was estimated that the midget itself, with a submerged capability –
for C.A.2, C.A.3 or C.A.4 – of no more than 70nm (80.5 miles, 129km), might
need to remain in the Hudson for up to two days. Yet, according to Borghese,
only Italy’s collapse in September 1943 prevented the mission from being
carried out, as planned, in December of that year. As well as the four
C.A.-type boats, the Italian Navy built 22 midgets of C.B.-type (some of them
completed under the Italian Fascist Republic in 1943–44). These four-man boats
of 36/45 tons (36.6/45.7 tonnes) were not used for “special attack” missions
but for conventional torpedo operations. In this role, they had some success in
the Black Sea, where a six-strong flotilla operating from the Romanian port of
Constanta is credited in Italian and German records (at variance with other
sources) with sinking the Soviet submarines Shch. 208, in June 1942, and Shch.
207 in August 1943.
