In the dark waters outside Alexandria in the early 1940s, a handful of Italian divers rode slow, unstable machines that looked more like plumbing projects than weapons. Their mission was to slip beneath British defenses, cling to the hulls of capital ships, and turn the harbor into a graveyard without firing a single conventional shot. What unfolded was an attack few Allied commanders had seriously anticipated, built around a weapon that fused improvisation, engineering, and raw nerve: the human torpedo.
I want to trace how that unlikely idea moved from rejected patent to battlefield shock, why the Italians were the first to make it work, and how their “pigs” forced navies to rethink what a secure harbor really meant. The story is not just about one spectacular raid, but about how a small group of frogmen and their fragile craft opened a new chapter in underwater special operations.
From rejected patent to Italian obsession
The concept of a man riding a torpedo did not begin in the Mediterranean, and it did not immediately inspire confidence. In 1909, the British designer Commander Godfrey Herbert secured a patent for a manned torpedo, only to see it rejected by the War Office as too radical and impractical for the fleets of the day, a reminder that navies often dismiss disruptive ideas before they are forced to confront them in combat, as later outlined in the Timeline of early underwater weapons. The British would eventually return to Herbert’s vision, but not before another navy seized the initiative and proved that a human-guided torpedo could do what conventional submarines and air raids could not.
That breakthrough came with the first truly practical human torpedo, the Italian maiale, an electrically propelled craft driven by a 1.6 horsepower (1.2 kW) motor that traded speed for stealth and control in confined waters. Italian engineers designed the maiale as a slow-running vehicle that could carry two divers, who would ride it like a small submersible, detach a warhead for use as a limpet mine, and then attempt to escape, a configuration detailed in accounts of the Italian program. By the time the Second World War was fully under way, the Italians had turned Herbert’s discarded idea into a doctrine built around patience, precision, and the willingness to put human beings at the very tip of the spear.
Inside the “pigs”: design, training, and tactics
The maiale, nicknamed “pig” by its own crews, was a study in compromise, a weapon that demanded as much from its riders as from its machinery. In operation, these human torpedoes were usually carried to their targets by a conventional submarine, then launched close to enemy anchorages so the frogmen could guide them the rest of the way, a method described in technical histories of the maiali. Once in the water, the divers had to fight currents, mechanical failures, and the constant risk of detection as they nudged their slow craft through harbor defenses that had been designed to stop fast-moving torpedoes and full-sized submarines, not two men clinging to a metal cylinder.
Accounts of Italian training describe how The Italians drilled their frogmen to work in near-total darkness, relying on touch and simple instruments while wearing heavy suits, oxygen cylinders, and masks that limited visibility and endurance, a regimen recalled in descriptions of The Maiale. The key to the operation was not speed but the ability to descend underwater, cut through anti-submarine netting, and clamp explosive charges onto the hulls of target ships, a painstaking process that required the riders to leave their vehicle, work by feel beneath steel giants, and then retreat before the timed mines detonated, as detailed in reconstructions of frogmen tactics.
Alexandria: the night the harbor went silent
The most famous test of this strange weapon came when the Italian Navy sent six men toward the British fleet at Alexandria, using maiali that were so temperamental the crews themselves called them pigs. On December 16, Italian planners aimed their slow-running torpedoes at three British ships outside Alexandria harbor, betting that a handful of divers could achieve what surface attacks and air raids had failed to do, a plan later summarized in accounts of how the Italian navy embraced the human torpedo. The frogmen slipped into the harbor, navigated past defenses, and planted mines beneath the battleships that formed the backbone of British power in the eastern Mediterranean.
When the charges detonated, they severely damaged HMS Queen Elizabeth, HMS Valiant, and the destroyer HMS Jervis, knocking them out of action for months and stunning Allied commanders who had believed Alexandria to be secure, as later images and commentary on the Raid on the harbor make clear. Their Decima Flottiglia MAS, the Italian special unit behind the attack, had delivered one of the most daring and successful operations of the Second World War, and later retrospectives on Decima Flottiglia MAS note that this success helped convince navies of the potential of underwater special operations. The attack did not win the war for Italy, but it forced the British to reckon with a new kind of threat that could bypass their guns and armor entirely.
Copycats and countermeasures: British and German responses
Once the shock of Alexandria faded, other navies moved quickly to copy and adapt the Italian idea, turning human torpedoes into a contested technology rather than a one-sided advantage. The British developed their own version, The Chariot, a human torpedo used in World War II that drew direct inspiration from Italian operations and was fielded in several raids before being withdrawn from operational use in 1943, as summarized in technical notes on Chariot development. The British Chariot carried Two frogmen who rode in tandem, guiding the craft toward enemy ships, detaching the warhead, and then attempting to escape, a method that mirrored Italian tactics but reflected British engineering preferences, as described in analyses of The British Chariot.
The German navy also experimented with its own manned torpedoes, including the Neger, a one-man vehicle that carried a torpedo slung beneath its hull and had a range of 48 nautical miles, a design that traded crew redundancy for simplicity, as detailed in descriptions of the German Neger. By the time of Operation Overlord, the Neger and related craft were being deployed in coastal waters in an effort to harass Allied shipping, a late-war attempt to use small, expendable craft to offset overwhelming naval superiority, as later operational histories of the Neger recount. These copycat programs underscored how quickly a single unexpected success could reshape naval priorities, even if the technology remained dangerous and unreliable for its own crews.
Legacy of the “slow-running” revolution
For all their drama, human torpedoes were never a wonder weapon, and many missions ended in failure, capture, or death for the riders. Detailed reconstructions of Italian operations describe how frogmen would descend underwater, cut through anti-submarine netting, and clamp mines onto hulls, only to see some attacks thwarted by mechanical breakdowns or improved defenses, a pattern captured in analyses of slow-running torpedo raids. Yet even when individual missions failed, the broader concept proved resilient, because it exploited a structural vulnerability: large warships are most exposed when they are stationary in supposedly safe harbors, surrounded by fixed defenses that can be studied, mapped, and eventually bypassed.
Naval planners took note, and over time, the techniques pioneered by Decima Flottiglia MAS and their peers helped shape the doctrine of modern special operations forces that operate beneath the waves. Later assessments of early frogmen emphasize how Their Decima Flottiglia MAS operations at Alexandria and elsewhere set a standard for courage and innovation that influenced the evolution of naval special warfare, as highlighted in retrospectives on Their legacy. The human torpedoes developed by these units were crude by modern standards, but they showed that small teams with specialized equipment could infiltrate defended waters, damage an enemy ship, and return, a pattern later echoed in analyses of how human torpedoes were used.
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*This article was researched with the help of AI, with human editors creating the final content.
