Part Seven: Torpedoes First in Anger
The first six parts of this series have considered the multitude of torpedoes acquired by the U.S. Navy. It seems appropriate now to explore briefly the combat use of these weapons. From 1890, when the Howell torpedo entered service, until the attack on Pearl Harbor the U.S. Navy appears to have fired only 11 torpedoes in anger. These torpedoes were fired by three of the seven A-boats of Sub Div Five against German U-boats during U.S. participation in WWI. No evidence of torpedo firings against enemy targets by U.S. Navy destroyers or torpedo boats prior to WWII has been found. There were very few enemy surface vessels operating in the patrol areas or along convoy routes during the period of U.S. involvement in WWI, and depth charges and gunfire were more effective against submarines. No torpedoes were fired in anger by the U.S. Navy between the wars and I would argue, probably with very little objection, not enough were fired for test and evaluation purposes. The main torpedo activities between the wars were the development of the Mk 13, Mk 14 and Mk 15 standard torpedoes and the now notorious Mk 6 exploder. The attack on Pearl Harbor brought about an immediate change. Over 100 torpedoes were fired by U.S. submarines against enemy targets during December 1941. During WWII the United States produced about 65,000 torpedoes of all Marks and Mods. And submarines, destroyers, destroyer escorts, aircraft and PT boats fired about 17,000 against enemy targets. This massive use of torpedoes, which is considered in more detail later, accounts for all but 19 of the total number fired in anger by U.S. forces. Eleven of the 19 have already been noted. The remaining eight were Mk 13 torpedoes dropped by five AD Skyraiders of VA-195 and three Skyraiders of VC-35 operating from USS PRINCETON on 1 May 1951.Their target was the Hwachon dam in Korea about 50 miles northeast of Seoul. This dam was used by the Communists to make a moat of the Pukham River. Major attempts by each of the
services failed to damage the dam. As something of a last resort, it was decided to attack the dam with torpedoes. Of the eight torpedoes, six detonated on target, one missed and there was one dud. The sluice gates of the Hwachon dam were permanently opened. These were the last eight torpedoes fired in anger by the U.S. Navy. There have been, however, a few fired by other navies since the end of wwn. Among these, USS LIBERTY was seriously damaged by one of three torpedoes fired by Israeli torpedo boats in 1967, the Indian frigate KHUKRI was torpedoed by the Pakistani submarine BANGOR in 1971 and two venerable Royal Navy Mk 8 torpedoes sank the Argentinean cruiser GENERAL BELGRANO in 1982. Since the end of WWD, the primary role of torpedoes in the U.S. Navy has been as an ASW threat. This role will be discussed in more detail in a subsequent article.
U.S. Navy Torpedoes in World War U; Surface and Air Launched Attacks
Of the 17,000 torpedoes fired by U.S. forces against enemy targets during WWII, over 14,000 were fired by submarines. Over 1400 torpedoes were dropped by aircraft and the remainder were fired by destroyers, destroyer escorts and PT boats. In terms of sinkings, the effectiveness of torpedoes fired by surface vessels was limited. Including enemy vessels sunk in surface actions by torpedoes or by torpedoes and gunfire, the count is about 40.2 On l December 1941 the U.S. Navy had 171 destroyers in commission. Through 14 August 1945 another 362 were commissioned or reverted to destroyer status, while 69 were sunk, one captured and 86 stricken or reclassified. In its original configuration, each of these destroyers had between five and sixteen 21 inch torpedo tubes. All told there were four or five thousand torpedo tubes mounted on U.S. Navy destroyers during WWII. The tubes of the WWI design flush deckers fired Mk 8 torpedoes and the newer
ships fired Mk 15s. It seems very likely, however, that well over half of the torpedo tubes were never fired at an enemy target. This, of course, was because opportunities for destroyers to fire torpedoes at the enemy without endangering friendly forces were limited and because of the multitudinous other tasks assigned to these versatile ships. In spite of this and other difficulties destroyers attacked a significant number of enemy ships with torpedoes. These torpedoes sank about a dozen Japanese warships and shared credit with gunfire for others. In may ways, the most famous of the U.S. surface torpedo actions was that of DesRon 23 (Arleigh Burke’s Little Beavers) in the Battle of Cape St. George on 25 November 1943. Torpedoes sank the Japanese destroyer ONAMI, torpedoes and S inch gunfire sank MAKINAMI and gunfire alone sank YUGIRI. Also notable was the Battle of Surigao Strait (25 October 1944) in which the Imperial Japanese Navy lost two battleships, FUSO to destroyer launched torpedoes and YAMASHIRO to destroyer launched torpedoes with what appears to have been a minor assist from gunfire. U.S. destroyer escorts mounted three 21 inch torpedo tubes in a single triple mount. These tubes were seldom fired, again for lack of opportunity, and there is no evidence that any significant enemy surface warships were sunk. In the Battle off Samar, however, USS SAMUEL B. ROBERTS (DE 413) fired her three torpedoes at an unidentified Japanese cruiser scoring one hit. The intrepid small boy was sunk later in the battle.
On the first of December 1941 the U.S. Navy had 29 PT boats. During the war 476 more were commissioned, there were 69 war losses and 71 others that were transferred, reclassified or stricken. Roughly the first 187 PT boats were fitted with 21 inch torpedo tubes that fired Mk 8 torpedoes. A small number of later PT boats were fitted with tubes for 22.5 inch torpedoes, which were in long supply. Most of the balance of these commissioned into the U.S. Navy were fitted with Mk 1 Mod 1 launchers which could launch either 21 inch Mk 8 or 22.5 inch Mk 13 torpedoes over the side. Most boats carried four tubes or launchers, but some had only two. Again one sees a large capacity for launching torpedoes which, for a variety of reasons, was not extensively used. PT boats sank about half a dozen German and Japanese warships. The Japanese destroyers TERUZUKI, UZUKI and KIYOSHIMA (the last credit shared with Army Air Forces aircraft) were probably the largest warships sunk by PT boat torpedoes. Several German torpedo boats and corvettes also fell victim to U.S. PT boat torpedoes. Rear Admiral Oldendorf used 39 PT boats at the battle of Surigao Straits, primarily to warn of Japanese incursions. Most of the torpedoes carried by these vessels, possibly as many as 156, were fired but all missed. Marksmanship notwithstanding, these PT boats managed to report the progress of Vice Admiral Nishimura’s force through the strait and in this way contributed significantly to the victory. Further, PT boats played important roles in coastal operations including barge busting. These other roles proved more important than the original one of firing torpedoes against surface vessels.
When the United States entered WWII, Navy torpedo squadrons were equipped with Douglas TBD torpedo bombers each capable of carrying one Mk 13 torpedo, a close cousin to the Mk 14 and Mk 15. These TBDs served, and many were expended, through the Battle of Midway (June 1942). Beginning in June the TBDs were replaced by Grumman TBFs and later the essentially identical Eastern TBM. The total production of TBFITBM aircraft was close to 10,000. The U.S. Navy received over 8500 of them and about 1000 went to Britain and Australia. Mk 13 production amounted to 16,600 torpedoes. According to a post war review 1287 Mk 13s were dropped by carrier based aircraft for 514 (40 percent) hits and an additional 150 Mk 13 torpedo attacks were made by land based aircraft. The main point is that the number of aerial torpedo attacks was relatively small and less than 10 percent of the production. During WWII torpedoes accounted for only 12 percent of the total weight of bombs, torpedoes and mines expended by U.S. Navy and Marine Corps aircraft against shipping and 25 percent of that expended against warships. The most spectacular successes were the sinking of the super battleships, MUSASHI in 1944 by 11 torpedoes (two duds) and about 20 bombs and YAMATO in 1945 by 10 torpedoes and five bombs.
Most of the crucial damage to these enormous, 64,000 ton standard displacement ships was done by the torpedo hits. Several carriers were sunk by air launched torpedoes or combinations of torpedoes and bombs. The largest was the 25,675 ton standard displacement ZUIKAKU. This ship was hit by five torpedoes and four bombs at the Battle of Cape Engano in October 1944. One of the reasons for the limited use of aerial torpedoes was the inability to launch them from high altitude or at high speed. The Mic 13 torpedo in use through mid-1944 was limited to launch from 50 feet or less at speeds of 110 knots or less. These limitations were removed in mid-1944 by adding a plywood drag ring, pickle ba”el to the nose and a plywood stabilizer to the tail. Other improvements were made and 1944 was a banner year for the Mk 13; over half of those dropped during the war, 781, were dropped in that year. These changes were made, not as a result of NTS Newport efforts, but as a result of National Defense Research Committee work primarily at the California Institute of Technology. It was not only the submariners who suffered from the neglect of the torpedo station.
In addition to the Mk 13 torpedoes, 142 Mk 24 homing torpedoes were dropped by U.S. forces against enemy submarines. Twenty-six German and five Japanese submarines were sunk and another 15 damaged. The importance of the Mk 24, however, is not so much in these numbers as in the fact that it was the first U.S. homing torpedo and the first anti-submarine torpedo. As such it together with its siblings and progeny pointed the way to post war torpedo development and the dominance of torpedoes in ASW.
U.S. Navy Torpedoes in World War Two: Submarine Attacks
There were 112 submarines in commission at the time of U.S. entry into WWII. In the course of the war another 201 were commissioned. Seven submarines were transferred to Britain after 7 December and 53 were war losses or marine casualties.
Twenty-one older boats were decommissioned before the end of the war. Thus, 313 U.S. submarines were in commission at one time or another during WWII and 266 of these made at least one war patrol. The average number of war patrols per boat was over six and STINGRAY made 16. The total number of war patrols was almost 1700 as shown below in Table I. In the course of these patrols over 14,000 torpedoes were fired, mostly Mks 14, 18 and 23, which collectively accounted for about 12,500 of the total. The remainder were Mk 9, Mk 10, Mk 11, Mk 12, Mk 15 and homing torpedoes Mk 27 and Mk 28. The breakdown of torpedo firings by mark, command and year is given in Table II (at the end of this article).
Table I . WWII Submarine Patrols by command
These efforts were a major contribution to the war in the Pacific. Sinkings included the battleship KONGO, four carriers, SHOKAKU, TAIHO, UNYO and SHINYO, 13 cruisers, 40 destroyers, 18 submarines and about 125 others to make a total of 201 naval vessels. Japanese merchant ship losses to U.S. submarines totaled 1113 vessels of over 500 tons (totaling 4,779,902 GRT). The grand total of 1314 ships sunk by U.S. submarines was almost half of all Japanese ships of all types sunk during WWII by U.S. forces.
Problems with U.S. Navy torpedoes have been noted in many places, including an earlier article in this series. It seems appropriate to ask what impact these problems had on the progress of the war. That question cannot be answered with sweeping statements covering the entire war, but it does seem possible to consider the submarine war in three phases 1941-42, 1943 and 1944-45. The first period was characterized by major changes in the composition of the Submarine Force. The number of submarines increased from 112 to 134. This net change was the result of the commissioning of 36 new submarines, the transfer of six boats to Britain, four marine casualties and four war losses. Ten of the 14 deletions were R-boats or S-boats. In addition, beginning in July 1942 Shoats were returned to the States. After 1942, except for four patrols, the S-boats operated from Alaskan bases and in the Atlantic. Thus 1942 was a transition year and the transition was even more pronounced when capability was considered. At the end of 1942, 64 of the 134 boats could load 24 torpedoes as compared to only 31 on 8 December 1941. Thirty of the 112 submarines that were in commission on 8 December 1941 had torpedo data computers (TDC) Mk 1 and the 36 new boats bad TDC Mk 3. Beginning in June 1942, SJ radars were installed in new construction and retrofitted to submarines in commission. During the 13 months of this first phase, slightly over 2000 torpedoes were fired in the course of 460 war patrols (315 if patrols in Atlantic waters and those originating in Alaska are excluded). Somewhat over half of the torpedoes were Mk 14. Five hundred and seventy-one torpedoes (28 percent) hit their targets. Nineteen Japanese naval vessels and 148 merchant vessels were sunk by U.S. submarines through 31 December 1942. The major torpedo problems during this first period were: 1} inadequate supply, 2) deep running of the Mk 10 and Mk 14 torpedoes, 3) erratic runs, and 4) exploder problems. All of these problems were important, but in terms of sinking ships, the most important was the shortage of torpedoes. If every submarine going on patrol had carried a full loadout of torpedoes and if the firing of spreads had not been discouraged, the number of torpedoes fired could have been 30 to SO percent higher and a concomitantly larger number of Japanese ships might have been sunk. Next in significance was deep running. The significance of this defect is difficult to appraise simply because there is no data. Certainly some of the almost 1400 misses were due to deep running, but the problem was well known to the operators, if not to BuOrd and Newport, and setting torpedoes to run shallow was not an uncommon practice.
Comparing the percentage hits for 1943, after the depth problem had been fixed, with that for 1942, when the depth problem was in full swing, shows 35 percent hits for 1943 and 29 percent for 1942. Thus it seems reasonable to conclude that if the depth problem had been fixed in 1940 or 1941, as it should have been, the percentage of hits in the first phase of the submarine war would have been higher by about six percentage points. This would imply 200 sinkings of enemy ships as opposed to the actual 167. For the entire war SubPac reported 141 erratic runs and 179 exploder failures out of 8474 torpedoes fired, a combined 3.74 percent. This was much worse early in the war. seven percent through 30 June 1943, primarily because of premature and magnetic influence exploder failures. Putting all this together, it appears that with an unlimited supply of infallible torpedoes, an additional 100 or so Japanese ships might have been sunk between 7 December 1941 and 31 December 1942. This would probably have shortened the war a little, perhaps a month or two, but certainly not a year. None of this, however, excuses the way that Newport dealt with torpedo supply and performance. Since these failures were discussed in Part Two of this series we will not say more about them here.
Calendar year 1943 was much better for the U.S. Navy Submarine Force. With an average of about 160 boats in commission and the old S-boats largely relegated to Alaskan operations and less demanding patrolling in the Atlantic, 323 patrols departed for Pacific operating areas during the year. On these patrols over 3700 torpedoes, 11.5 per patrol vice 6.3 for 194142, were tired. Over 1300 hits (35 percent) were scored resulting in the sinking of 22 Japanese naval vessels and 293 merchantmen. The improvement came from several sources. All of the 56 boats commissioned in 1943 and most of the older boats making patrols in the Pacific had TDCs and SJ radar and thus greatly enhanced capability to make good attacks. The availability of accurate radar range information, ±25 yards out to six mile range,9 combined with the ability of the TDC to verify target motion parameters and produce good fire control solutions was an important advance. Further, most boats could load 24 torpedoes and the torpedo shortage was mostly over.
The depth problem had been fixed toward the end or 1942. The magnetic influence exploder, which failed to detonate the warhead in some cases and caused prematures in others, was disabled on torpedoes used by ComSubPac patrols in June and finally by ComSubSoWesPac in December. The impact exploder problem was identified and fixed in the last half of the year. All patrols out of Pearl Harbor after 14 October 1943 carried torpedoes with modified contact exploders. The Mk 14 was not absolutely reliable, but it was, in most respects, a good weapon, far better than it had been in December 1941. It is interesting to note that of the 26 patrols on which five or more enemy ships were sunk, only four departed on patrol before 14 October 1943. One disastrous problem, circular runs, remained. This problem affected both the Mk 14 and the Mk 18 and may not have been a pure torpedo problem. We will return to this issue later. In addition to the improvements in the Mk 14, the Mk 18 electric torpedo began to arrive at Pear Harbor. It had teething problems including fires and explosions due to accumulated hydrogen gas and cold batteries that caused slow running and missing astern, but these and other problems were fixed rather quickly through collaborative efforts of the operating forces and Westinghouse, the manufacturer. The wakeless Mk 18 was not, however, the panacea that had been expected. A wartime study showed that the significance of wake detection by lookouts had been over estimated and that the lower speed of the electric torpedo was a distinct disadvantage. The only discernible effect of the study was the important one of keeping the Mk 14 in production. Submariners either didn’t know about the report or chose to ignore or disbelieve it. They continued to worry about wake detection and the Mk 18 became very popular and an important weapon in the last years of the war.
The last 20 months of the war saw the fully evolved might of the U.S. Navy Submarine Force. In 1944 U.S. Navy submarines made 520 patrols in the Pacific and sank a total of about 630 ships, 1.2 sinkings per patrol. This should be compared with about 1.0 sinkings per Pacific patrol during 1943 and about 0.5 per patrol in 194142. Seventeen of the 26 patrols on which five or more enemy ships were sunk departed in 1944. The percentage hits for Mk 14 and Mk 23 torpedoes in 1944 was slightly over SO percent and over 32 percent for Mk 28s. For the eight months of war in 1945, torpedo performance was statistically not as good, but the number of torpedoes fired and the number of torpedoes fired per patrol were also much smaller. There were still problems with individual torpedoes as one would expect with any complicated mechanical device. The winding down of the war in 1945 is apparent in the detailed statistics.
The overall performance of torpedoes as reported by SubPac is presented in Table ID. On the basis of this table and the foregoing discussion we feel that torpedo problems had a definite, but relatively small effect on the progress of the war in the Pacific. There are three important caveats that go with this statement. First the effect of torpedo failures on the morale of submarine crews was very significant. Cold statistics cannot deal with this issue, but these crews were at the sharp end of the stick and their morale should have had a higher priority with the stateside establishment. Second, the way BuOrd and NTS Newport dealt with reports of torpedo problems from the operating forces was scandalous. Reports of suspected problems should have been meticulously investigated by the torpedo establishment without endless prodding.12 Third there are torpedo system failures that endanger the firing submarine and these should be considered separately from failures that cause only misses. The most notable of this class of failure are circular runs.
At least 20 circular runs have been reported for the WWII period. One of these was responsible for the loss of TANG and another was probably responsible for the loss of TULLIBEE. The first wartime circular run occurred in December 1941 and they continued at least through December 1944 (at least 20 post-WWU circular runs of Mk 14 torpedoes, one with a live warhead, have also been reported).13 Most circular runs involved Mk 14 or Mk 23 torpedoes, but a few, including the one that sank TANG were Mk 18s. So far we have found no evidence that Buord or any part of the torpedo establishment made any effort during WWII to determine what caused circular runs for these Marks. Circular runs are not mentioned in the torpedo chapter of SubPac’s Submarine Operational History. Nor have we found evidence of significant efforts'” to develop a protective device that would, for example, shut down the torpedo propulsion system if its course. went more than say ± 135 degrees from the course of the firing submarine and so make such failures/all safe. Circular runs with Mk 14 torpedoes continued at least until 1968-69. The wartime homing torpedoes with gyro controlled enabling runs, the developmental Mk 27-3 and Mk 28 did, however, have anti-circular run safety systems and the practice seems to have continued with post WWII torpedoes.
The combat history of U.S. Navy torpedoes is totally dominated by the 45 months of WWII. Starting from a position of relatively poor preparation, defects were found and, with unfortunate slowness, corrected. As with many other kinds of war materiel, new civilian production was brought into play and shortages of torpedoes were alleviated. Torpedoes were launched during WWII with good effect by aircraft and surface vessels, but the natural marriage of submarines and torpedoes produced prodigious results sinking 201 Japanese naval vessels and 1113 merchantmen. The end of WWII brought a change in the environment in which torpedoes were developed and we will discuss this last half century in the next article.