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CDR Alden is a World War II submarine veteran and the recognized authority on the reconciliation of US and Japanese records of US submarine sinkings of Japanese ships during World War II. He is a frequent contributor to THE SUBMARINE REVIEW.

According to Japanese records, two auxiliary submarine chasers, KAMO MARU and KURAMA MARU, were sunk by a submarine on 18 July, 1944 in the vicinity of Balabac Strait, between the northern tip of Borneo and the southern tip of Palawan in the Philippines. On that same day USS LAPON (SS 260) made an attack in the same general area and claimed sinking two ships. No other attack by a U.S. submarine was reported on or close to 18 July anywhere in that part of the South China Sea, and a respected reference publication, Warships of the Imperial Japanese Navy. 1869-1945, attributed the downing of the two little ships to LAPON. The case appeared to be cut and dried. In addition, the subchasers were just spitkits, too small to be included in the official tally of U.S. submarine sinkings and therefore of little interest to researchers. There were a few small discrepancies between the Japanese and American accounts, but I chalked them off as probably misprints or garbles in one or another of the records, and there the matter rested until recently.

In the course of reviewing my data on U.S. and Allied submarine attacks, I had occasion to look more closely at the two cases in question, and found that what had appeared to be trivial discrepancies were far more controversial. There were significant differences in the details of the attacks as described in the respective U.S. and Japanese sources, making it much less probable that LAPON had downed the sub chasers. Were the Japanese records mistaken in claiming that a submarine was the agent? If not LAPON, could another sub possibly have been involved?

First, I think we can reject the possibility that the Japanese were mistaken in attributing the sinkings to a submarine. There have been several cases where Japanese ships mistook explosions for torpedoes when they were most likely mines, but the Japanese records describe the subchasers as engaging in a running gun battle with a surfaced submarine, and there were no Allied surface ships in the area in July 1944. As for the possibility that LAPON was mistakenly credited with the sinkings, we need to look more closely at the records.

The Japanese accounts are sketchy and in parts contradictory, but the most definitive source, as translated by my colleague Erich Muehlthaler, tells a reasonably clear story. On 15 July 1944 three auxiliary subchasers-KIKU MARU, KAMO MARU, and KURAMA MARU – left Manila en route to Kudat, a port near the northern tip of Borneo just south of Balabac Strait. The craft were sisters, former steam trawlers of 233 or 234 gross tons built in 1920. They had been commandeered by the Japanese Navy, anned, and converted into subchasers. Just after midnight on 18 July the KIKU MARU reported being in a running battle with a submarine between 08-44N 116-41 E and 08-40N 11 6-30E, during which she fired six rounds from her 12 cm mortar and dropped two depth charges. KURAMA MARU also reported being shelled by an enemy sub that night, with five crewmen killed. KIKU MARU rescued the survivors and reached Kudat the same day. However, KURAMA MARU was not seen again, and the records show her as sunk at 08-00N l 14-38E. As for KAMO MARU, she reportedly dropped out of sight on the 181th and was presumed to have been sunk by a torpedo 160 nautical miles SSW of Cape Buliluyan (a point at the southern tip of Palawan lsland) or at the geographic coordinates 08-00N I 14-38E, with the loss of her entire crew of 15. The Japanese records do not explain the basis for the presumed location-the same position as given for her sister, KURAMA MARU.

What is odd about the reported position is that it places the sinkings of KURAMA MARU and KAMO MARU about 180 miles from KJKU MARU’s running battle. There are indications in the records that some positions may be approximate if not inaccurate. For instance, in different accounts the location of the subchasers is given with reference to various points on the map-off Balabac Straits, 150 nm NW of lesselton, and 120 nm WNW of Cape Kudat-in addition to the geographic coordinates cited above. One source dates KURAMA MARU’s sinking at 8 rather than 18 July, probably a typographical error. Another source also warns that some of the data were “probably generated by Allied records.” Unfortunately, we don’t know which, if any, of the positions are suspect. The reliability of the printed records will become an issue when we compare them with LAPON’s attack report.

LAPON was on her fifth patrol, the fourth under command of Lowell T. Stone. At about midnight between 17 and 18 July Stone made three night surface torpedo attacks against a small convoy consisting of two medium AKs and one escort at position 08-20N I 16-40E. This is close enough to KIKU MARU’s running battle to be within the range of differences often found between U.S. and Japanese accounts of the same encounter. However, the cargo ships described by Stone hardly resemble 233-ton spitkits.

Stone’s first attack was made at 2035 (H zone time) on the very dark night of 17 July. The targets were medium coal-burning AKs of about 4,000 tons with split superstructures, approximately 400 feet long. It stretches the imagination to think that an experienced skipper like Stone could have mistaken little trawlers for these cargo ships. Six bow tubes were fired at overlapping targets without results, although the fish ran hot, straight and normal and should have hit. At 2208 four more torpedoes were fired from the stem tubes at the same ship, this time with running depth set at three feet. Two timed explosions were seen and heard, the target smoked heavily, slowed, separated from the other AK, and disappeared from the radar screen at 5,000 yards. Stone was sure that it had sunk, and placed its position at 08-22N 11 6-45E.

The escort then departed, abandoning the remaining AK, which made a radical course change and headed for the nearest land about 40 miles away. At 0013 on the 18th, back at the original position of 08-22N 116-40E, Stone fired four bow tubes at this target, which he described as having the same characteristics as the first AK, and observed one or two hits followed by a spectacular explosion. Globules of molten metal and pieces of hull rising in the air gave the effect of a fireworks display accompanied by flames of every color. When the sub passed through the position 20 minutes later, no wreckage was found. Yet here again the fact that two attacks almost four hours apart were made at exactly the same position, although both submarine and target were moving the entire time, raises doubts about the accuracy of LAPON’s position reports. In fact, just before the attack started the sub hit a floating log that knocked out the pitometer log, which could have seriously affected the accuracy of its plotted positions.

According to other Japanese records. LAPON’s victim was actually KYODO MARU #36, a 1,499-ton converted survey ship, that was torpedoed and sunk at LAPON’s exact position (an indication that it too might have been “generated by Allied records”). Oddly enough, only one man was reported killed.

If LAPON did not sink the subchasers, could another submarine have been responsible, and if so, which one? There was apparently another submarine in the area, because at 0740 on 16 July LAPON sighted and avoided a periscope at 07-22N l 14-52E. The brief entry in the patrol report implies that Stone may not have known that another friendly sub was in the vicinity and therefore avoided what he thought could have been a Japanese boat. In any case, he made no attempt to identify the stranger. If it was a U.S. submarine and it attacked the subchasers two days later, it never reported the engagement. Yet if the positions stated in the records are correct, the unknown boat could have been as close as 20 miles from LAPON during its running battle with the subchasers!

According to published U.S. accounts, ROBALO (SS 273), under Lt. Cdr. Manning M. Kimmel, left Fremantle, Australia, on 22 June 1944 to patrol in the South China Sea until 2 August. Thereafter, her only direct contact with shore was a radio message on 2 July reporting having sighted Japanese warships east of Borneo, and when she failed to return from patrol she was given up as lost. However, information was later received from Philippine guerrillas that ROBALO sank on 26 July off western Palawan, probably after hitting a mine. Four survivors reached shore, but were captured by the Japanese and imprisoned at Puerto Princesa. On 15 August they were transferred to a Japanese destroyer and never heard from again. However, while still in prison one of the men had dropped a note to another U.S. prisoner, who passed it on to the local guerrillas, from whom the word ultimately reached American authorities.

Since ROBALO was clearly in the South China Sea within the right time period, why had Kimmel not reported sinking the subchasers? By that stage of the war gun attacks on small craft by U.S. submarines were quite common, but normally they were not of sufficient importance to warrant breaking radio silence in order to report them. Most were only mentioned in the written patrol report well after return to port. No other submarine ever reported sinking the subchasers and ROBALO was the only boat missing during the time period and in the ocean area in question. With LAPON eliminated as a contender, only ROBALO is left as the U.S. submarine that could have sunk the Japanese vessels.

My ultimate conclusion is that ROBALO was indeed the submarine responsible for sinking KURAMA MARU and KAMO MARU. Given the absence of positive evidence, this is inherently speculative, but I think the case is strong. Although they are still on eternal patrol, Manning Kimmel and his gallant crew deserve this belated recognition for a hitherto unrecorded success against the enemy.

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