Frogman

A frogman is someone who is trained in scuba diving or swimming underwater. The term often applies more to professional rather than recreational divers, especially those working in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word frogman first arose in the stage name the "Fearless Frogman" of Paul Boyton in the 1870s and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit.
The term frogman is occasionally used to refer to a civilian scuba diver, such as in a police diving role.
In the United Kingdom, police divers have often been called "police frogmen". Some countries' tactical diver organizations include a translation of the word frogman in their official names, e.g., Denmark's Frømandskorpset; others call themselves "combat divers" or similar.

Scope of operations

Tactical diving is a branch of professional diving carried out by armed forces and tactical units. They may be divided into:

Combat or assault divers.
Special mission work divers, who do general work underwater.
Work divers who are trained in defusing mines and removing other explosives underwater.

These groups may overlap, and the same men may serve as assault divers and work divers, such as the Australian Clearance Diving Branch.
The range of operations performed by these operatives includes:

Amphibious assault: stealthy deployment of land or boarding forces. The vast majority of combat swimmer missions are simply to get "from here to there" and arrive suitably equipped and in sufficient physical condition to fight on arrival. The deployment of tactical forces by water to assault land targets, oil platforms, or surface ship targets is a major driver behind the equipping and training of combat swimmers. The purposes are many, but include feint and deception, counter-drug, law enforcement, counter-terrorism, and counter-proliferation missions.
Sabotage: This includes putting limpet mines on ships.
Clandestine surveying and reconnaissance: Surveying a beach before a troop landing, or other forms of unauthorized underwater surveying and reconnaissance in denied waters.
Clandestine underwater work, e.g.:
* Recovering underwater objects.
* Clandestine fitting of monitoring devices on submarine communications cables in enemy waters.
Investigating unidentified divers, or a sonar echo that may be unidentified divers. Police diving work may be included.
Checking ships, boats, structures, and harbors for limpet mines and other sabotage; and ordinary routine maintenance in war conditions.
Underwater mine clearance and bomb disposal.

Typically, a diver with closed circuit oxygen rebreathing equipment will stay within a depth limit of with limited deeper excursions to a maximum of because of the risk of seizure due to acute oxygen toxicity. The use of nitrox or mixed gas rebreathers can extend this depth range considerably, but this may be beyond the scope of operations, depending on the unit.

Mission descriptions

US and UK forces use these official definitions for mission descriptors:
; Stealthy: keeping out of sight when approaching the target.
; Covert: carrying out an action of which the enemy may become aware, but whose perpetrator cannot easily be discovered or apprehended. Covert action often involves military force which cannot be hidden once it has happened. Stealth on approach, and frequently on departure, may be used.
; Clandestine: it is intended that the enemy does not find out then or afterwards that the action has happened – for example, installing eavesdropping devices. Approach, installing the devices, and departure are all to be kept from the knowledge of the enemy. If the operation or its purpose is exposed, then the actor will usually make sure that the action at least remains "covert", or unattributable.

Defending against frogmen

Anti-frogman techniques are security methods developed to protect watercraft, ports and installations, and other sensitive resources both in or nearby vulnerable waterways from potential threats or intrusions by frogmen.

Equipment

Frogmen on clandestine operations use rebreathers, as the bubbles released by open-circuit scuba would reveal them to surface lookouts and make a noise which hydrophones could easily detect.

Origins of the name

A few different explanations have been given for the origin of the term frogman.

Paul Boyton adopted the stage name The Fearless Frogman. In the 1870s, he was a long distance swimmer who wore a rubber immersion suit, with hood.
In an interview with historian Erick Simmel, John Spence claimed that the name "frogman" was coined while he was training in a green waterproof suit, "Someone saw me surfacing one day and yelled out, 'Hey, frogman!' The name stuck for all of us."
History

In ancient Roman and Greek times, there were instances of men swimming or diving for combat, sometimes using a hollow plant stem or a long bone as a snorkel. Diving with snorkel is mentioned by Aristotle. The earliest descriptions of frogmen in war are found in Thucydides' History of the Peloponnesian War. The first instance was in 425 BC, when the Athenian fleet besieged the Spartans on the small island of Sphacteria. The Spartans managed to get supplies from the mainland by underwater swimmers towing submerged sacks of supplies. In another incident of the same war, in 415 BC, the Athenians used combat divers in the port of Syracuse, Sicily. The Syracuseans had planted vertical wooden poles in the bottom around their port, to prevent the Athenian triremes from entering. The poles were submerged, not visible above the sea level. The Athenians used various means to cut these obstacles, including divers with saws. It is believed that the underwater sawing required snorkels for breathing and diving weights to keep the divers stable.
Also, in the writings of Al-Maqrizi, it is also claimed that the naval forces of the Fatimid Caliphate, in an engagement with Byzantine forces off the coast of Messina henceforth referred to as the Battle of the Straits, employed a novel strategy with strong similarities to modern-day frogmen tactics. In the writings of Heinz Halm, who studied and translated the writings of Al-Maqrizi and other contemporary Islamic historians, it is described: "They would dive from their own ship and swim over to the enemy ship; they would fasten ropes to its rudder, along which earthenware pots containing Greek fire were then made to slide over to the enemy ship, and shattered on the sternpost." Apparently, this tactic succeeded in destroying many Byzantine vessels, and the battle ended in a major Fatimid victory; according to the Arab historians, a thousand prisoners were taken, including the Byzantine admiral, Niketas, with many of his officers, as well as a heavy Indian sword which bore an inscription indicating that it had once belonged to Muhammad.
The Hungarian Chronicon Pictum claims that Henry III's 1052 invasion of Hungary was defeated by a skillful diver who sabotaged Henry's supply fleet. The unexpected sinking of the ships is confirmed by German chronicles.
On 4 November 1918, during World War I, Italian frogmen sunk the Austro-Hungarian ship Viribus Unitis.
Italy started World War II with a commando frogman force already trained. Britain, Germany, the United States, and the Soviet Union started commando frogman forces during World War II.

First frogmen

The word frogman appeared first in the stage name The Fearless Frogman of Paul Boyton, who since the 1870s broke records in long distance swimming to demonstrate a newly invented rubber immersion suit, with an inflated hood.
The first modern frogmen were the World War II Italian commando frogmen of Decima Flottiglia MAS which formed in 1938 and was first in action in 1940. Originally these divers were called "Uomini Gamma" because they were members of the top secret special unit called "Gruppo Gamma", which originated from the kind of Pirelli rubber skin-suit nicknamed muta gamma used by these divers. Later they were nicknamed "Uomini Rana," Italian for "frog men", because of an underwater swimming frog kick style, similar to that of frogs, or because their fins looked like frog's feet.
This special corps used an early oxygen rebreather scuba set, the Auto Respiratore ad Ossigeno, a development of the Dräger oxygen self-contained breathing apparatus designed for the mining industry and of the Davis Submerged Escape Apparatus made by Siebe, Gorman & Co and by Bergomi, designed for escaping from sunken submarines. This was used from about 1920 for spearfishing by Italian sport divers, modified and adapted by the Italian navy engineers for safe underwater use and built by Pirelli and SALVAS from about 1933, and so became a precursor of the modern diving rebreather.
For this new way of underwater diving, the Italian frogmen trained in La Spezia, Liguria, using the newly available Genoese free diving spearfishing equipment; diving mask, snorkel, swimfins, and rubber dry suit, the first specially made diving watch, and the new A.R.O. scuba unit. This was a revolutionary alternative way to dive, and the start of the transition from the usual heavy underwater diving equipment of the hard hat divers which had been in general use since the 18th century, to self-contained divers, free of being tethered by an air line and rope connection.

Wartime operations

After Italy declared war, the Decima Flottiglia MAS attempted several frogmen attacks on British naval bases in the Mediterranean between June 1940 and July 1941, but none were successful, because of equipment failure or early detection by British forces. On September 10, 1941, eight Xª MAS frogmen were inserted by submarine close to the British harbour at Gibraltar, where using human torpedoes to penetrate the defences, sank three merchant ships before escaping through neutral Spain. An even more successful attack, the Raid on Alexandria, was mounted on 19 December on the harbour at Alexandria, again using human torpedoes. The raid resulted in disabling the battleships and together with a destroyer and an oil tanker, but all six frogmen were captured. Frogmen were deployed by stealth in Algeciras, Spain, from where they launched a number of limpet-mine attacks on Allied shipping at anchor off Gibraltar. Some time later they refitted the interned Italian tanker Olterra as a mothership for human torpedoes, carrying out three assaults on ships at Gibraltar between late 1942 and early 1943, sinking six of them.
Nazi Germany raised a number of frogmen units under the auspices of both the Kriegsmarine and the Abwehr, often relying on Italian expertise and equipment. In June 1944, a K-Verband frogman unit failed to destroy the bridge at Bénouville, now known as Pegasus Bridge, during the Battle of Normandy. In March 1945, a frogman squad from the Brandenburgers was deployed from their base in Venice to destroy the Ludendorff Bridge over the Rhine which had been captured by the US Army in the Battle of Remagen. Seven frogmen swam downriver to the bridge carrying explosives, but were spotted by Canal Defence Lights. Four died, two from hypothermia, and the rest were captured.
The British Royal Navy had captured an Italian human torpedo during a failed attack on Malta; they developed a copy called the Chariot and formed a unit called the Experimental Submarine Flotilla, which later merged with the Special Boat Service. A number of Chariot operations were attempted, most notably Operation Title in October 1942, an attack on the German battleship Tirpitz, which had to be abandoned when a storm hit the fishing boat which was towing the Chariots into position. Operation Principal in January 1943 was an attack by eight Chariots on La Maddalena and Palermo harbours; although all the Chariots were lost, the new Italian cruiser Ulpio Traiano was sunk. The last and most successful British operation resulted in sinking two liners in Phuket harbour in Thailand in October 1944. Royal Navy divers did not use fins until December 1942.
Late in the war, the Imperial Japanese Navy formed a Special Attack Unit of suicide divers, called Fukuryu. The were to be armed with a 10kg mine on a long pole for use against Allied landing craft. Equipment consisted of a loose wet suit, a large rigid helmet and tanks attached back and front. It was intended that in the event of an invasion, they could wait underwater for up to ten hours, close to the shore and protected from bombardments by submerged concrete shelters. A training program was run at Kawatana and Yokosuka, during which there were many fatal accidents caused by the rudimentary equipment. Some 1,200 divers had completed the course by the end of the war, with a further 2,800 still in training.