The Italian Atomic Bomb II

Preparations for deployment of nuclear arms may have begun in Italy almost a year before the Luebeck blast witnessed by Hans Zinsser, when a specimen of the Regia Aeronautica’s only four-engine heavy bomber appears to have been specifically modified to accommodate such a weapon. The Piaggio P.133 was an advanced version of the P.108B, unique not only because a single example was produced, but due to its unusual streamlining. The standard crew of ten men was reduced to just two–pilot and navigator/ bombardier–while both its armor-plating and defensive machine-guns were stripped to afford a heavier payload.

The quartet of 1,500-hp Piaggio P.XIIRC.35 eighteen-cylinder radial engines was upgraded for improved power, and the bomb-bay enlarged. Although the lone P.133 was never officially designated an ‘atomic bomber’, extraordinarily high security surrounding its manufacture, together with the suggestive features of its design alterations, left some post-war historians wondering if the big Piaggio was intended to drop a nuclear bomb amid the Allied fleets massing for the invasion of the Italian mainland after the fall of Sicily. The P.133 might have been ready to participate in such a mission, but, clearly, no such device was yet available.

The Piaggio had to be modified for its unique task by Mussolini’s air force technicians, because Italy’s only purpose-built nuclear bomber fell into Allied hands after the Badoglio armistice of September 1943. Although officially known as a ‘transport’, the Savoia-Marchetti S.M.95 was ordered by the Regia Aeronautica at a period in the war when such a model was not needed, even senseless, which alone casts serious doubts on the real intention of its designers. Powered by four Alfa Romeo engines, it was twenty-three meters long, with a thirty-five-meter-wing span, which afforded it a tremendous lifting capacity. But the monster’s outstanding feature was its prodigious range of 12,005 kilometers. The S.M.95’s ability to carry a heavy payload over great distances suggest to some aviation historians that the ‘transport’ was actually intended to deliver a heavy bomb to cities along America’s Eastern Seaboard.

The idea for an aerial assault on New York originated with Piaggio’s chief test pilot, Nicolo Lana, in April 1942. He volunteered to fly a stripped-down P.23R, a tri-motor that had established several long-distance records before the war, dropping a single 1,000-kg. bomb on the city center, then ditching near the Nantucket Lighthouse, where he and his flight engineer would be picked up by a waiting submarine. His simple scheme offered every prospect of success. U.S. coastal defenses during the first half of 1942, when German U-boats prowling off America’s eastern shores scored some of their greatest successes, were appallingly weak. Unfortunately for Lana’s plan, the only P.23R in existence was destroyed in a landing accident near Albenga, and no other Italian plane had the Piaggio’s outstanding range.

Had the mission been carried out, damage to New York would have been inconsequential, but the effect on Allied morale at a time when the war was not going well for the Western powers would have made a powerful impact, resulting in a triumph for Axis propaganda. Strategically, the consequences could have been no less significant, as the Americans would have doubtlessly diverted much-needed resources and manpower to protecting North America from further attack.

Despite the P.23R’s mishap, Air Staff commanders had been intrigued by Lana’s proposal, but realized the Regia Aeronautica did not possess another plane that could fly the distance to New York without stopping en route for refuelling by a submarine-tanker, an overly complex operation made all the more hazardous by increasingly effective Allied counter-measures. A new aircraft conceived specifically for such a mission needed to be designed and built. Hence, the Savoia-Marchetti S.M.95. Under cover as a ‘transport’, its first prototype flew on 8 May 1943. Performance was very good, military modifications were made, and flight-testing began on 2 September. Six days later, the Badoglio government switched sides, and the imminent mission was scrubbed. When the lone SM.95 was seized by Badoglio’s government authorities, RSI planners were forced to modify the conventional Piaggio for the same purpose supposed to have been fulfilled by the four-engined Savoia-Marchetti.

Underscoring the probability of Regia Marina preparations for a specially redesigned aircraft able to carry an atomic bomb was the German Luftwaffe’s simultaneous modification of its own heavy bomber, the Heinkel He. 177 Greif, or ‘Vulture’. According to military air historian, David Mondey, work on a Greif at the Letov plant, in Prague, was intended “to provide an enlarged bomb-bay to accommodate the planned German atomic bomb”. The conversion began in late 1943, just when the Piaggio was being redressed in Italy. Not coincidentally, some of the German nuclear research was at that time being carried out in Czechoslovakia, where the Heinkel bomber was also converted to carry an atomic device. It would appear then, that both German and Italian Air Force officials anticipated the availability of atomic bombs sometime in late 1943.

One may only surmise that the contemporary political upheaval and de facto civil war that afflicted Italy with the arrest of Mussolini and subsequent turmoil in the wake of Badoglio’s September armistice prevented transportation of the delicate, top secret, fissionable materials and valuable equipment from reaching the Piaggio’s airstrip. The bomb intended for its sortie against the Allied invasion fleet may have been, moreover, a hastily packaged contingency than a real finished product, and the Italo-German physicists welcomed Italy’s temporarily stabilized military situation as a necessary breathing-space to properly finalize their many years of work in the creation and deployment of a true weapon less encumbered by the potentially disastrous uncertainties inherent in incomplete research.

While tactical use of a nuclear weapon against the Anglo-American invasion of Italy may have been the most practical option envisioned for it by the Commando Supremo, the propaganda value of such a device would not have been missed by Mussolini or men like Julio Valerio Borghese. Borghese was Commander of the X Light Flotilla, whose human-torpedoes had scored spectacular successes against British ships at Alexandria and Gibraltar. With America’s entry into the war on 9 December 1941, he believed these unconventional submersibles represented Italy’s best hope for striking the U.S. mainland. Borghese recalled later, “the psychological effect on the Americans, who had not yet undergone any war offensive on their own soil, would, in our opinion, far outweigh the material damage which might be inflicted. And ours was the only practical plan, so far as I am aware, ever made to carry the war into the United States.”

Beyond its obvious propaganda value, such an attack would sink several valuable freighters, and New York’s important harbor might be sufficiently damaged, as was the port of Alexandria, to close it for lengthy repairs. Far more significantly, following the attack, the Americans could be counted upon to divert substantial effort, materials and weapons from their war effort for the reinforced defense of not only New York, but the entire eastern seaboard, just as the Japanese withdrew many of their forces to protect Tokyo after it had received unimportant damage from 1942’s Doolittle raid. German V-1 missile attacks against London two years later prompted a similar reaction from the British. As the Doolittle raid raised American morale after months of uninterrupted bad news, Borghese’s New York operation would have an identical impact on Italian spirits. Potential repercussions–strategically, economically and psychologically–would certainly pay high military dividends on a meager investment in men and materiel.

The Duce and Commando Supremo heartily approved the scheme in late January 1942, and Borghese got to work on it immediately. The operation was set to take place in mid-December, when daylight would have been minimal and the extended darkness allowed his crews maximum time to carry out the operation. After dark, their vessel was to be delivered into the waters off Fort Hamilton. From there, it would cruise up the Hudson River to the merchant shipping docks along West Street, where ‘frogmen’ in scuba-gear would attach explosive charges to five or six freighters. After scuttling their submersible, the crews could choose to either surrender or go into hiding. Several thousand U.S. dollars were, in fact, provided each man, in the event he chose to avoid capture.

Due to the limited range of the Maiale human-torpedoes which attacked the British Fleet at Alexandria, Borghese envisioned using one of the Regia Marina’s pocket-submarines then operating with good success in the Black Sea against the Soviet Navy. But these ‘midgets’ were still too large for accommodation aboard a standard ocean-going submarine on a transatlantic mission from Europe to North America. Instead, he resurrected an earlier two-man submersible known as the Goeta-Caproni Project (after the inventor, Vincenzo Goeta, and its parent company), inaugurated in 1936.

Following extensive redesign, especially for silent running, two examples of the craft, which had been stored and almost forgotten for the previous six years, were tested under conditions of extreme secrecy in secluded Lake Iseo, later the site of another top secret undertaking, Churchill’s alleged Allied-Axis alliance against the Soviet Union. One of the submersibles sank irretrievably to the bottom of the lake, but the other achieved an operational range of 113 kilometers while cruising beneath the surface at six knots, performing admirably at forty-five-meter depths.

Renamed CA 2, it was ready for action by mid-summer 1942, when Borghese contacted Admiral Karl Dönitz. The commander of the German U-boat arm was intrigued by the project’s innovative audacity, but expressed his regret that he simply could not spare a single Milchkuh, or ‘Milk Cow’ submarine-refueller as a carrier for the CA-2 until late fall. Borghese knew that would not leave him enough time to make the necessary modifications, install the submersible, or test and train with it, so he visited the Italians’ Atlantic submarine headquarters at Bordeaux. Rear-Admiral Romolo Polacchini, the base commander, was enthusiastically taken with the proposal, for which only the Regia Marina’s best submarine was good enough, in his opinion.

Lieutenant Gianfranco Priaroggia’s Leonardo Da Vinci had just returned on 1 July after sinking 20,000 tons of Allied merchant shipping in the course of a single patrol, and both commander and submarine seemed ideally suited for the New York operation. The capacious Marconi class vessel could easily accommodate the CA 2, after its forward deck-gun and mounting were replaced by a cradle between the resistant hull and superstructure. Two large cranes on either side of the cradle lifted the pocket-submarine in or out of its cradle in which it rested, its upper one-forth exposed above decks. Both cranes folded away automatically into their own watertight compartments. “The operation against New York,” Borghese stated, “had passed out of the planning stage into that of practical operation.”

The complicated remodeling went under way with thorough but unusual haste, allowing extensive sea trials to begin on 9 September. The equipment and procedures required some adjustments, but the CA 2 with its two crew members was consistently released and recovered without difficulty, even in somewhat rough seas. Before month’s end, Lieutenant Priaroggia announced both his Leonardo Da Vinci and the midget-submersible were ready to undertake their mission. Borghese proudly notified his superiors in Rome, informing them that he would sail for New York on 19 December. The attack was scheduled to commence during the Winter Solstice. But too his shock and dismay, the Supermarina responded that the mission must be postponed for another year.

“New technological developments” then still in the making would render the operation far more effective than if it were attempted in 1942. Since such a surprise attack was a singular undertaking that could not be repeated, its maximum destructive potential had to be assured. No further explanation was given, although Borghese agreed that if the CA 2 could be eventually provided with more powerful explosive charges, as implied in the Supermarina communication, the long wait would be worthwhile. In the meantime, he pulled military strings to have additional pocket-submarines built and tested.

For the New York attack the CA-Class was heavily modified with the torpedoes removed and four large mines instead added to a remodeled superstructure. A diver lock-out compartment was built into the hull with hatches on both top and bottom. This allowed the frogmen to access the midget submarine directly from the dry interior of the host submarine.

Planned Special Forces attack on New York, 1943

The Leonardo Da Vinci had her deck-gun restored after the CA 2 was removed, but all other modifications for the submersible were undisturbed in preparation for the rescheduled 1943 mission, as Priaroggia was promoted to Lieutenant Commander “for outstanding service in war” on 6 May. But seventeen days later, his submarine was depth-charged by the British frigate, Ness, and a destroyer, HMS Active, just off Cape Finestrelle. There were no survivors. By this time, the war in the Atlantic had drastically shifted against all Axis vessels, both under and on the sea, but Borghese was undeterred in his determination to hold the Supermarina to its word: New York must be attacked during the next Winter Solstice.

He turned from submarines to aircraft as the alternative delivery system for his CA 2. The specimen he chose was one of the outstanding airplanes of the war, a maritime reconnaissance model with exceptional flight characteristics. The CANT 511 was originally designed in September 1937, as the world’s largest double-pontoon hydroplane, intended for civilian flights carrying mail, cargo and sixteen passengers between Rome and Latin America. The thirty-four-ton aircraft was powered to a cruising speed of 405 km/hr by four 1,350-hp Piaggio PXII C. 35 radial engines. At the time of its maiden flight, in October 1940, five months after Italy’s entry into the war, the 511 was converted into a military role. Final testing took place between late February and early March 1942, when test pilot Mario Stoppani succeeded in taking off and landing the fully loaded CANT in rough seas with three-meter waves and winds gusting between fifty and sixty-five km/hr.

This extraordinarily rugged stability and the hydroplane’s exceptional range of 5,000 kilometers seemed ideally suited for special, unconventional missions, including plans to free fifty Italian pilots and soldiers imprisoned in far-off Jeddah with a commando raid. Using the CANT to bomb Bathumi and Poti, Soviet Black Sea ports, or Baku, on the Caspian Sea, and the Persian Gulf’s oil facilities at Bahrain, were seriously considered. But Borghese laid claim to the only pair of 511s before these schemes could be sanctioned, and had the machines transported to Lake Treviso for modification.

Seating arrangements and cargo areas were torn out to make room for a pair of human-torpedoes. Ezo Grossi, who had since replaced Rear-Admiral Romolo Polacchini as the Italian base commander at Bordeaux, provided a large, ocean-going submarine-tanker to rendezvous at prearranged coordinates with the giant hydro-planes on two separate occasions–once coming and going across the Atlantic Ocean–to refuel the sea-planes en route to the target.

While such air-sea refuelling stops had been undertaken by Italian crews earlier in the war, none, of course, were conducted over such immense distances made especially perilous by Allied supremacy at and over the sea. Even so, renovation of the 511 began in June 1943, and proceeded with determination until the air frame suffered some damage during a low-level run by USAAF fighters. Repairs commenced at once, but before they could be completed the Italian armistice was announced on 8 September, and the project abandoned. At sixty tons, however, the CA 2 was too heavy to be carried by any aircraft, so Borghese returned to the Maiale for his New York attack.

As intriguing as the operation itself was its sudden postponement in late 1942, when men and equipment were ready to carry out their mission. The suspension occurred just as Piaggio’s alleged ‘atomic bomber’ was waiting for a nuclear device to be installed in its specially modified bomb-bay. Did the Supermarina delay the New York attack by twelve months because Mussolini expected to have an atomic bomb at his disposal by late fall or early winter 1943? His overthrow in mid-summer of that year rendered that project mute, at least until he could assert his new political base in Salo. Certainly, by April 1945, he talked as though such a weapon were about to fall into his hands.

Whatever documentation may have specified an Italian nuclear device must, of necessity, have been highly restricted. If such documentation did exist, it may still lie buried in the undisclosed archives of British intelligence. Naturally, such information would have been classified as the most secret of all and restricted to only very few supreme officials on a strictly need-to-know basis. The paper trail left by a weapon with the potential to reverse the course of history must have been necessarily scant and thoroughly covered up by the authorities. Abundant, if circumstantial evidence nonetheless suggests that the Italians were on their way to building an atomic bomb in the late 1930s. From 1942, they combined their efforts with German physicists in a joint attempt to deliver an operable device in time to win the war for the Axis. Hence, the Duce’s urgent appeal to his forces to “hold out for another month”.

As early as fall 1942, his scientists may have informed him that the bomb would be ready by late the following year, when the singular Piaggio P.133 stood by to receive its unique payload, and Borghese’s human-torpedoes would have been ready to attack New York with something more than a few explosive charges magnetically fixed to the hulls of freighters tied up at the West Street dock. Political upheavals, however, intervened to prevent the deployment of such advanced weaponry.

Someday future investigators probing the declassified files of British intelligence may find wartime documents outlining the extent of nuclear research undertaken by Fascist Italy and Nazi Germany. Perhaps when such important papers come to light they could reveal that New York City missed becoming history’s first victim of a nuclear holocaust by margins too narrow to contemplate.