The acumen of World War Two Imperial Japanese Navy cruiser and destroyermen in torpedo attack is an accepted fact. The range and power of their Type 93 torpedo (dubbed the "Long Lance" by historian Morison) have become the stuff of legend. To call the Japanese surface forces the best at torpedo attack is easily defensible.

But were they good enough to meet the standard required for their own strategic and tactical preconceptions? Prior to Admiral Yamamoto Isoroku's radical break with pre-war IJN strategy, the accepted method of engaging the US Fleet was a three fold process:

1. Attrition operations by submarines and surface force raids.
2. A night attack by fast battleships, Class A cruisers, and Special Type destroyers.
3. A daylight battle line engagement at dawn following the night attack. If the officer in tactical command judged it appropriate, the battle line could be committed to the night attack if that effort was going better than expected.

Torpedo attack was the cornerstone of the night attack, and a critical element of the day attack intended to rectify Japan's initial 3:5 and worsening deficit in numbers. The night attack force was to launch an intricately coordinated long-range salvo of 130 torpedoes from 11 different groups using half their ready torpedoes. This salvo was designed to converge upon and hit 10 American capital ships with 20 weapons (a rate of ~15%).

After the initial salvo at long range (20,000 meters), the four Kongo Class battleships and 17 Class A cruisers detailed to the night attack force were to break through the American screen - suicidally if necessary - and clear the way for the force's two torpedo cruisers and the light cruiser and 14 destroyers of a destroyer squadron to expend the remainder of their ready torpedoes in a close range attack from as little as 2,000 meters.

Once all ready torpedoes were expended, the night attack force was to fight its way clear, reload torpedoes, and execute further attacks if possible. Survivors would eventually join the battle line for the "Decisive Battle" at dawn.

The daylight Decisive Battle was also to feature torpedo attack, including an initial salvo of 280 weapons at long range. As this salvo began to hit, the battle line would open fire. This massive salvo was expected to cripple or sink 10 American capital ships. When the Japanese Admiral judged the situation ripe, the three light cruisers and 48 destroyers of three destroyer squadrons would charge (again, suicidally if necessary) to close range and expend the remainder of their torpedoes. This charge was expected to be able to ensure the destruction of 16 American capital ships.

The IJN's battle plan reads impressively and dramatically, but it has numerous flaws. Most of these will not be discussed in this article. Here the principle question is thus:

Did the Japanese achieve the required 15% hit rate necessary to successfully execute their pre-war strategic conception of a Decisive Battle, had they fought the war in such fashion?

An examination of the historical record is necessary. During the Pacific War, there were 27 surface engagements of note:

Of these I've rejected six for consideration due to their lack of any resemblance to the type of engagements that would take place in the Decisive Battle scenario, for the following reasons:

The elimination of these actions from consideration in no way diminishes the measure of IJN effectiveness. In fact, including the results of the torpedo attacks (or lack thereof) in these actions would materially degrade the IJN's score. In five of the actions, no torpedoes appear to have been launched, and in one other action between 40 and 56 weapons were launched with between 0 and 5 hits scored (the most likely number was 1).

Additionally, the ratio of combat forces engaged in the six actions eliminated was typically far greater than the IJN could expect to obtain at any point but after a successful conclusion of the Decisive Battle scenario.

The records available to me for many of these actions lack detail and do not specifically indicate the number of weapons fired by which ship, at which target, at what time, range and speed setting, and in some cases outright conflict. In some instances more detailed information was available. In these cases I state firm numbers. In others I qualify my estimates as "probable."

My estimates are based upon several factors where available:

1. Best resolution of data from multiple sources.
2. Documented actions of other ships in the same action, particularly if belonging to the same unit (Cruiser Division, Destroyer Squadron, etc...).
3. Apparent Japanese torpedo firing doctrine at the time of the battle.

Prior to the First Naval Battle of Guadalcanal (13 Nov 42), Japanese torpedo firing doctrine appears to have been to fire half the torpedoes in the tubes in one salvo, then fire the remainder in a second salvo, then reload all tubes fired.

From the First Naval Battle of Guadalcanal through the Battle of the Komandorski Islands (26 Mar 43), torpedo firing doctrine appears to have been in flux, with some ships/units firing two half salvos and then reloading while others completely empty their tubes in a single salvo and then reload.

After the Battle of the Komandorski Islands, torpedo firing doctrine appears to have shifted to firing all tubes in a single salvo and then reloading.

In all fairness, I have included duds as hits in my calculations, choosing not to damn the aiming torpedoman for fuze failures. All actions included for consideration have been related to a type of action that might take place in the context of executing the Decisive Battle's several phases. As few actions as possible have been eliminated in order to best represent IJN performance under conditions of both advantage and adversity. To merely assume that conditions would always favor the Japanese during the execution of their plan (even if it succeeded) violates Murphy's First Law of Combat: "No operations plan survives first contact with the enemy."

The synopses of the twenty-one surface actions under consideration follow:

3. The Battle of Badung Strait

Three RNN CLs, one DD, and eight MTBs and six USN DDs made a three wave attack on the IJN forces in Badung Strait. In two distinct phases of action, two and then four IJN DDs fended the ABDA ships off of the transports they were protecting. During the action, two IJN DDs launched a probable total of 8 Type 93 torpedoes, scoring 1 hit which sank the RNN DD Piet Hein. This is a probable hit rate of 12.5%. This action fits into the Decisive Battle scenario as representative of the potential of small units to hold off significantly larger forces.

4. The Battle of the Java Sea

One USN CA and four DDs, one RN CA and three DDs, one RAN CL, and two RNN CLs and two DDs attempted to attack the IJN invasion convoy headed for Java. Two IJN CAs, two CLs, and 14 DDs fended off the ABDA ships and inflicted serious losses on the opposing force but failed to destroy it completely. During the action the IJN ships executed 38 separate launches of a probable 164 Type 93 torpedoes, scoring 3 hits which sank the RNN CL De Ruyter, CL Java and DD Kortenaer. This is a probable hit rate of 1.8%, dismal for such a massive expenditure. This action fits into the Decisive Battle scenario as representative of a medium size engagement between one of the beam line Japanese night attack groups and a significant portion of the US screen. It shows how mutual maneuvering for position can deny both the attacker his objective and the defender decisive damage to the attacker.

6. The Battle of Sunda Strait

One USN CA and one RAN CL attempted to escape the Java Sea debacle via Sunda Strait where they ran into a Japanese landing in progress. Two IJN CAs, one CL and nine DDs scattered about the area moved to intercept, sinking the two intruders. During the action the six IJN ships executed 7 launches of a probable total of 37 Type 93 torpedoes, scoring 5 hits which sank USN CA Houston and RAN CL Perth. This is a probably hit rate of 13.5%. This performance is marred by an additional five hits scored on IJN transports and a minesweeper by a misaimed launch from CA Mogami. This action fits into the Decisive Battle scenario as representative of the chaos of having a small hostile unit slip into the midst of multiple friendly formations. This would cut both ways during the projected night battle.

7. The Battle of Savo Island

Five IJN CAs, two CLs and one DD attacked the landings at Guadalcanal, overcoming four USN CAs, one RAN CA, and seven DDs guarding the anchorage. Confused, damaged and separated into three formations, the Japanese force withdrew without exploiting its victory to attack the transport area. During the action the eight IJN ships executed 15 launches of 45 Type 93, 4 Type 8 and 12 Type 6 torpedoes, scoring 7 telling hits and 1 dud which damaged USN CA Chicago and sank USN CAs Vincennes and Quincy. This is a hit rate of 13.1%. This action fits into the Decisive Battle scenario as representative of one of the beam line night attack units engaging a significant portion of the US screen. It clearly shows the effect of confusion on even a force which is winning.

8. The loss of USS Blue

Having dropped off its Tokyo Express run, an IJN DD encountered two USN DDs escorting a pair of transports, making an attack of opportunity. The IJN DD crippled one USN DD which was later scuttled, but failed to follow up its success. The IJN DD made a probable single launch of 4 Type 93 torpedoes, scoring 1 hit which crippled USN DD Blue. This is a probable hit rate of 25%. This action fits into the Decisive Battle scenario as representative of how a small isolated unit can inflict damage, but not necessarily capitalize on it in the interests of self preservation.

9. The Battle of Cape Esperence

A USN force of two CAs, two CLs, and five DDs looking to intercept a Tokyo Express run encountered and ambushed its covering force of three IJN CAs and two DDs. The USN forces sank one CA and one DD and severely damaged a second CA, handing the IJN its first defeat in a surface engagement, but failing to intercept the supply run. During the action, one CA may have conducted a launch of at least 2 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as an example, on a small scale of how an attacker can be surprised and defeated in disorder.

10. The First Naval Battle of Guadalcanal

A USN force of two CAs, three CLs and eight DDs intercepted an IJN force of two BBs, one CL, and eleven DDs, successfully preventing a bombardment of the island's airfield, but suffering heavy losses in the effort. During the action, the IJN conducted eight launches of 48 Type 93 torpedoes, scoring six hits which crippled USN CLs Atlanta and Juneau, and USN CA Portland, and sank DDs Barton and Laffey. This is a hit rate of 12.5%. This action fits into the Decisive Battle scenario as an example of how even a powerful attacking detachment can be repulsed with losses by screening units.

11. The Second Naval Battle of Guadalcanal

A USN force of two BBs and four DDs intercepted an IJN force of one BB, two CAs, two CLs, and eleven DDs, successfully preventing a bombardment of the island's airfield, again at significant loss in the effort. During the action, the IJN conducted a probable fourteen launches of a probable 51 Type 93 torpedoes, scoring 2 hits which crippled USN DD Benham and sank USN DD Walke. This is a probable hit rate of 3.9%. This action fits in the Decisive Battle scenario as an example of what could happen to even a powerful attack unit should it come up against an alert and ably led element of the US Battle Line.

12. The Battle of Tassafaronga

A USN force of four CAs, one CL and six DDs botched an ambush of eight IJN DDs on a Tokyo Express run. The IJN ships conducted a very successful torpedo counterattack and escaped for the sacrifice of one of their number. During the action, the IJN DDs conducted a probable eight launches of a probable 47 Type 93 torpedoes, scoring six hits which crippled USN CAs Minneapolis and New Orleans, damaged CA Pensacola and sank CA Northampton. This is a probable hit rate of 12.7%. This action fits into the Decisive Battle scenario as an example of how scattered and surprised formations can reform and execute a decisive counterattack.

13. The Battle of the Komandorski Islands

A USN force of one CA, one CL and four DDs impetuously attempted to attack IJN transports in the Aleutians despite a strong escort of two IJN CAs, two CLs and five DDs. The IJN force aborted the supply run and held off the USN force, which was lucky to escape without serious loss. During the action, the IJN conducted nine launches of 42 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as an example of what might occur between scattered screening elements during the daylight phase of the action.

14. The Battle of Kula Gulf

A USN force of three CLs and four DDs ambushed a Tokyo Express run of ten IJN DDs, sinking one, damaging three and driving another aground, at the price of one CL. During the action, the IJN conducted four or five launches of a probable 36 Type 93 torpedoes, scoring 3 hits, sinking USN CL Helena. This is a hit rate of 8.3%. The action fits into the Decisive Battle scenario as an example of what could happen to a destroyer unit hitting an inner screen detachment.

15. The Battle of Kolombangara

An Allied force of two USN CLs, one RNZN CL, and ten USN DDs intercepted a Tokyo Express run of one IJN CL and five DDs, paying heavily for sinking the IJN CL. During the action, the IJN conducted a probable ten launches of a probable 80 Type 93 torpedoes, scoring 4 hits and 1 dud which damaged USN CLs Honolulu and St. Louis, crippled RNZN CL Leander, and sank USN DD Gwin. This is a probable hit rate of 6.25%. This action fits into the Decisive Battle scenario as a counterexample to the previously cited battle.

16. The Battle of Vella Gulf

A USN force of six DDs ambushed a Tokyo Express run of four IJN DDs, sinking three in a nearly perfect torpedo attack. During the action, the IJN conducted one launch of 8 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as an example of an action between light elements of both the attacking and defending forces.

17. The Battle of Horaniu

In a little known and mutually embarrassing action a USN force of four DDs tangled with an IJN force of four DDs. Neither side managed to harm the other. During the action, the IJN conducted four launches of a probable 26 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as another example of a small unit action.

18. The Battle of Vella Lavella

A force of six USN DDs attacked a Tokyo Express run of nine IJN DDs and came off the worse. During the action, the IJN conducted a probable six launches of a probable 48 Type 93 torpedoes, scoring 2 hits which crippled USN DDs Selfridge and Chevalier (which was later scuttled). This is a hit rate of 4.1%. This action fits into the Decisive Battle scenario as another example of a small unit action.

19. The Battle of Empress Augusta Bay

An IJN force of two CAs, two CLs and six DDs attempted to break up a landing on Bougainvillea, and was routed by a USN force of four CLs and eight DDs for small loss. During the action, the IJN conducted seven launches of 44 Type 93 torpedoes, scoring 1 hit which crippled USN DD Foote. This is a hit rate of 2.2%. This action fits into the Decisive Battle scenario as an example, on a medium scale of how an attacker can be surprised and defeated in disorder.

20. The Battle of Cape St. George

A USN force of five DDs ambushed an IJN Tokyo Express run of five DDs, sinking three. During the action one IJN DD may have conducted two launches of 9 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as another example of a small unit action.

21. The Battle off Biak

IJN forces of one CA, one CL and five attempted to reinforce Biak, partly with towed barges of troops, but broke off its mission in a brief skirmish with a superior Allied cruiser-destroyer force which withdrew its 3 CLs before giving chase with three DD divisions. During the action the five IJN DDs each appear to have made a single launch of a probable 42 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as an example of what might happen to an attacking unit falling back before a clearly superior defensive unit.

22. The Battle of Surigao Strait

IJN forces of two BBs, three CAs, one CL and five DDs attempted to breach an Allied force of six USN BBs, three USN CAs, one RAN CA, four USN CLs, one RAN DD, and nineteen USN DDs. They were shattered and repulsed for small damage. During the action the IJN conducted a probable three launches of 20 Type 93 torpedoes, scoring 0 hits. This is a hit rate of 0%. This action fits into the Decisive Battle scenario as an example of what could happen to a strong element of the night battle force if it did penetrate far enough to open a path to the US Battle Line.

23. The Battle off Samar

An IJN force of four BBs, six CAs, two CLs, and eleven DDs debouched San Bernardino Strait and attacked a USN escort carrier task force of six CVEs, 3 DDs and 4 DEs. They became thoroughly disorganized by the USN DD/DE counterattack and aerial harassment, being repulsed with heavy losses. During the action the IJN conducted at least one launch of 7 Type 93 torpedoes, scoring 0 hits. This is a rate of 0%. This action fits into the Decisive Battle scenario as an example of how the destroyer charge could come apart and be ineffective, and how a countercharge can disrupt the attacking battle line.

26. The Battle of Ormoc Bay

A USN force of three DDs attacked an disrupted Japanese forces including two small DDs unloading troops into Leyte. They thoroughly shot up the IJN force, sinking a small DD, but failed to get away unscathed, losing one DD to a Japanese torpedo. During the action the IJN conducted at least one launch of 4 Type 93 torpedoes, scoring 1 hit which sank USN DD Cooper. This is a probable hit rate of 25%. This action fits into the Decisive Battle scenario as an example of a small unit action.

The table below summarizes these actions.

In these battles the IJN hit 30 enemy ships with 44 Type 93, 1 Type 8 and 2 Type 6 torpedoes in these battles, sinking 18. The average hit rate was 6.71%, far below the required 15%. Of 130 torpedoes in an opening salvo for the Night Battle, only 9 would find a mark, at an average of 1.6 per ship, resulting in hits on about six ships which would probably be two CAs, two CLs and two DDs. Of these, one of each would probably sink based off historical results. The 280 torpedo salvo at the start of the daylight Decisive Battle would net only 18 hits at a rate of 6.71%.

In terms of efficiency (rounds expended per hit obtained) the Japanese needed to achieve a rate of 6.67:1. In actuality, they achieved a rate of 16.76:1. Instead of achieving a hit rate equivalent to slightly more than one per average destroyer (8-tube Kagero Class) firing a full load, the IJN achieved a rate slightly worse than one per two full loads fired from an average destroyer.

To answer the question posed by this article; the IJN did not achieve the necessary hit rate or efficiency in action to make the Decisive Battle strategy a success, had that course been pursued. Even the world's best surface torpedomen were not good enough to bring the Decisive Battle to fruition for the IJN. All they could do was make it costly, and die fighting.

Two significant factors have not been included in this review for lack of sufficient reliable documentation.

The first is a review of the Type 93 torpedo by range fired, and speed setting employed. The dismal performance in such long-range actions as Java Sea and Komandorski Islands, and the relative success in the close-range actions of the Solomons Campaign, imply that the weapon's speed was a greater asset than its range. It may be that the Japanese misappreciated their own weapon and would have been better served by a plan which eschewed "long-range concealed firing" in favor of short-range attacks that offered the enemy less time to evade.

The second is a review of Type 93 dud and depth control problems. Numerous Type 93s failed to explode, many others ran under their targets and others prematured in the wake pattern of the target ship. Without detailed information on impact angles, Type 93 fuze characteristics, and the number of weapons which passed harmlessly beneath their targets, reliable observations regarding these factors (so famously poor in US submarine and aerial torpedoes) are impossible. What little information I have on these phenomena suggests the Type 93 was not immune to these banes of the torpedo designer and employer.

Only a handful of battles are documented well enough to yield exact totals. Thus, I was forced to make approximations based upon what I could observe of Japanese torpedo doctrine. For example, up until about half-way through the Solomons Campaign, Japanese doctrine was to fire half of their ready torpedoes in one salvo, empty the tubes with the next and then withdraw to reload. About mid-1943, they appear to have abandoned this doctrine in favor of flushing the tubes on the first salvo, then withdrawing to reload. I based this on some careful inference from Evans and Peattie about Japanese pre-war doctrine, and those firings that actually were well documented. Up through Komandorski islands, half-salvoes are used. From Kula Gulf on, full salvoes.

And, of course, there were exceptions both before and after July '43. I did my best to reconstruct the firing doctrine in effect at the time and applied that to the launches for which I lacked authoritative documentation.

• Kaigun by Evans and Peattie
• Japanese Cruisers of World War Two by LaCroix and Wells
• Disaster in the Pacifici by Warner and Warner
• The Battle of Cape Esperence by Cook
• The Naval Battle of Guadalcanal by Grace
• The Battle of the Komandorski Islands by Lorelli
• The Two-Ocean War by Morison
• A Battle History of the Imperial Japanese Navy by Dull
• Cruisers of World War Two, An International Encyclopedia by Whitley
• Cruisers of the US Navy 1922-1962 by Terzibaschitsch
• War Plan Orange by Miller
• US Warships of World War 2 by Silverstone
• Japanese Warships of World War II by Watts
• A History of War at Sea by Pemsel
• Atlas of American Wars by Natkiel
• Atlas of World War II by Natkiel

16 April 2000

Updated