The Solomons Campaign: Unleashing the Assassin’s Mace

Assassin’s mace (English adaptation of the Chinese phrase ‘shashou jiang’) — one periodically hears of the term used, usually in combination with advocacy for avoiding the same through transformational (forces)(TTP)(platforms)(weapons)(networks) – pick any, none, or all.  Most recently, the ASBM the Chinese are purported to be developing has served as the poster child for Assassin’s Mace, but ’twasn’t always so.  In the opening stages of the Pacific War, especially the period 1942-44, US forces were on the receiving end of a true assassin’s mace – the Long Lance torpedo.  How was that?  Well, let guest author, Chuck Hill (who will be bringing us the writeup on the 13/14 Nov 42 Guadalcanal action in the near future) explain… – SJS
P.S.  Of course we are well aware of the irony in using a Chinese phrase to describe a Japanese weapon.

Problems with American torpedoes are well documented. As a result of false economies and the arrogance of personnel charged with designing them, America’s new standard torpedoes, the Mk 13 air launch (also used by PT boats), the submarine launched Mk 14, and surface launched Mk 15, were never realistically tested before the war. They had problems which included the magnetic exploder, the contact exploder, and the depth keeping mechanism. But even if they had worked perfectly, American torpedoes were significantly inferior to Japanese surface and submarine launched torpedoes, as were every other torpedo in the world.

The giant 24 inch Type 93 “Long Lance” torpedoes in particular, were a secret weapon, expected to level the field with the numerically superior American Navy. Japanese pre-war planning had included special formations, the Night Battle Force (Yasen Butai) or Advanced Force, designed to exploit these torpedoes using night attacks. It was primarily the ships of the Advanced Force that would fight the night battles of the Solomons Campaign.

Like most of the torpedoes of the period, the most common Japanese surface vessel and submarine torpedoes were steam driven. In the case of the Japanese torpedoes, they burned Kerosene. Unlike virtually every other torpedo, they used pure oxygen rather than natural air to support combustion. Pure oxygen eliminated 77% of the gases of natural air that took up a great part of the volume of the torpedo, contributed nothing to the combustion process, but added considerably to the wake of the torpedo. This gave the torpedoes longer range at higher speeds with very little wake. Here is a statistical comparison of the respective surface launched torpedoes (from Campbell):

Not only were the torpedoes unique in their range and lethality. The supporting systems that employed the torpedoes were also unique. Oxygen generating systems were provided for topping up the pressure inside the torpedoes. Generally there was a reload torpedo for each tube and a system that allowed it to be reloaded in about 20 minutes. A notable exception was the torpedo cruiser conversions, Kitakami and Oi, equipped with no less than 40 torpedo tubes.  Cruisers typically carried 16 to 24 torpedoes and destroyers 16 to 18.

To take advantage of the increased range, in some installations, the Japanese used a firecontrol computer comparable to that used for controlling guns in an anti-surface mode, worked by five crewmembers, that was good to ranges of 40,000 meters. They also took extra care to insure that their torpedoes ran straight and true.

While the Zero fighter came as a nasty shock; it should not have been, because it had been employed before Pearl Harbor, and an American Naval Attache had sat in one at an air show outside Tokyo in 1940. At least its qualities were quickly recognized and tactics were changed in an attempt to neutralize its advantages relatively quickly. In the case of the Japanese torpedoes, American commanders made tactical errors throughout virtually the entire Solomons Campaign because the range of these torpedoes went unrecognized.  It did not have to have been that way, in a rare occurrence, a volunteer agent brought the American Naval Attache in Tokyo detailed information about the Type 93 Torpedo. … But in 1940, when the American Office of Naval Intelligence (ONI) offered this information to its customers, insisting that it came from an ‘impeccable’ source, the Navy’s Bureau of Ordinance declared such a weapon to be impossible. Neither the British nor the Americans had yet mastered oxygen technology, so it was inconceivable that the Japanese had done so.” (Aldrich, p 64) Later, a type 93 torpedo was recovered, but no one seemed in any hurry to let the people who were actually fighting the war know about its exceptional performance. (Crenshaw)

(crossposted at: USNI blog)

References:
Aldrich, Richard James, Intelligence and the War Against Japan, Cambridge Press, 2000
Campbell, John, Naval Weapons of World War Two, Conway Maritime Press Ltd, 1985
Chesneau, Roger, ed., Conway’s All the World’s Fighting Ships, 1922-1946, Conway Maritime Press Ltd, 1980
Crenshaw, Russell Sydnor, Jr., South Pacific Destroyer, Naval Institute Press, 1998
Dull, Paul S., A Battle History of the Imperial Japanese Navy (1941-1945), Naval Institute Press, 1978
Lacroix, Eric and Linton, Wells II, Japanese Cruisers of the Pacific War, Naval Institute Press, 1997