The T10, derived from the G7e, was powered by electric batteries, and had a maximum range of 6000yds (5500m) at 30 knots. On this basis it was purely a short-range, close-in defence weapon for ports and smaller harbours, to deny their use to an Allied invasion force. Sites were planned for the French coast, and in Belgium, Denmark, Holland and Norway. The following French ports and harbours were cited in German reports: Brest, Dunkirk, Calais, Boulogne, Fécamp, Le Havre, Port-en-Bessin, Cherbourg, Douarnenez, Audierne, Beg-Meil, Benodet, Larmor-Plage, Turballe, St-Nazaire, Royan, Bandol, Hyères, La Pallice, Marseilles and Toulon; in Belgium, Zeebrugge and Ostend. Although work proceeded on several of these, none ever became operational.
Launch was to be carried out by trolley, although at La Pallice a report mentioned a lowering device for the battery sited on the mole, so perhaps an underwater cradle was also planned. Again, at Royan a winch and crane were reported destroyed by Allied bombing. Tests refer to satisfactory engine starts at a depth of 0.5m.
The reasons for failure trickle through the progress update reports: lack of resources, Organisation Todt personnel deployed elsewhere, and enemy action. However, at the same time all was not well with the torpedoes themselves. To make their position known to the operator, the T10 could respond to an ‘up’ command and broach the surface. At night it could be made to flash lights for the same purpose. However, it was found that after this evolution, it was difficult to regain full directional control. The same control relay interfered with the magnetic pistol, which had to be removed.
The final modification cut the torpedo gyro after the first course command received by the torpedo, leaving just the control directional options of full left rudder, rudder central or full right rudder. The torpedo could also be set to circle. This was the definitive production model, but only a tiny handful was ever produced. No record remains of any Spinne war launch.
FUKURYU UNDERWATER INSTALLATIONS
A sketch prepared by USN intelligence officers in January 1946 shows the type of underwater diving chamber planned to be installed at various points around the coast of Japan in readiness for the expected Allied invasion of early 1946. The bases were to be manned by the ‘Fukuryu’ (‘Crouching Dragons’) frogmen of the ‘Tokkoyai ’, or Special Offensive Corps, the umbrella unit which organized the kamikaze suicide attacks on the Allied fleet.
The imaginative nature of the proposed installation is worthy of a Jules Verne story. The hidden nature of the underwater base, although at first sight ingenious, suffers from basic problems such as how to man it when the invasion arrives, and how do the occupants actually know where to find the attacking target vessels? They would need at least reliable waterproof underwater telephone lines from a shore-based observer. Again, the depth of water shown in the sketch would tend to negate the suicidal lunges of the Fukuryu armed with their 15kg spar torpedo at the end of a pole just a few metres in length. Finally, it was only to be expected that landing craft would try to steer well clear of underwater obstacles, such as a wreck.
It would appear that the American officers preparing the report had been obliged to interview surviving Fukuryu trainees, and extrapolate information as far as possible from verbal responses, since all documents were burned by the unit’s officers on 20 August, five days after the emperor’s radio announcement of the Japanese surrender.
Part III
Anti-torpedo Defence
CHAPTER 16
Active Defence
Initially, the practical means of defence against a torpedo was to spot its launch vessel, and simply outmanoeuvre the torpedo. In the early days of the Whitehead, the weapon’s limited speed and range performance meant that a well-handled armour-clad with an alert crew could, in ideal conditions of sea, visibility and steam availability, evade the attack by torpedo. However, early trials by the French navy indicated that an attack on a single battleship, even if her crew were forewarned, could succeed if at least three torpedo boats attacked simultaneously.
At the time of the introduction into service of the Whitehead, the turret and broadside armament of most modern warships consisted of rifled muzzle-loaded cannon, in the process of being supplanted in some navies by breech-loaders. Accuracy, range and penetrating power were being constantly improved, but these weapons offered scant security against a determined attack by torpedo boats. The guns were too large, too cumbersome to train quickly to follow a rapid target, their rate of loading was abysmally slow, and when they fired the target would be obscured by a thick cloud of propellant smoke.
MACHINE GUNS
Something more efficient was required. The introduction of mechanical, hand-cranked machine guns was a first step, although the French navy persisted in the hope that 11mm-calibre breech-loading magazine rifles, fired in volleys, could either drive off a torpedo boat or, even more optimistically, explode the warhead of its torpedo. Thus navies everywhere hastily began mounting rifle-calibre machine guns — Gatlings, Nordenfelts and Gardners — followed by upgraded models firing rounds up to one inch in diameter (25.4mm).
The Gatling had a high rate of fire even when hand-cranked, but fatal dispersion at longer range. The faster you turned the handle, so the point of impact varied because the moment of firing in the cycle changed. In the early 1900s the US Navy converted its Gatlings to electric motor drive, to give a rate of fire of up to a thousand rounds a minute. It was this late development, and not some theatrical revival of a Civil War Gatling as has sometimes been cited, which inspired General Electric in the 1960s to produce the Vulcan revolving cannon.
The fighting top underwent a revival, sometimes even castellated as in Tudor warships. Designed as a weapons platform to bring fire down on an enemy vessel’s deck and exposed gun crews during a close-quarters fight, it was found ideal for mounting the rapid-firing machine guns of the anti-torpedo boat armament. French ships even had electrically operated ammunition lifts inside their fighting masts, which detracted even further from their often tender stability.
French sailors on board the armour-clad Vauban during the 1890s, firing volleys from their 11mm Kropatschek magazine rifles. At upper left is a 37mm Hotchkiss revolver. (Painting by Paul Jazet, courtesy of the Musée de la Marine, Paris)
Ten-barrelled Gatling on a naval pedestal mount in the Turkish Naval Museum, Istanbul, captured from the Austrians, who manufactured it under licence. (Photo courtesy of Dick Osseman, www.pbase.com/dosseman)