If a Japanese admiral had paid more attention to the advice of a Prussian general, the history of the last war might take a little longer to tell. The general was Carl von Clausewitz, and his advice—the principle of concentration of forces. The admiral was Mineichi Koga, who realized that the principle applied to sea as well as land strategy, but violated the principle and suffered the consequences.
Koga was born of samurai stock in Kyushu, the home of so many Japanese naval officers. In 1906 at the age of twenty- one he graduated from the Naval Staff College and embarked on a distinguished career that included command of the battleship Ise, the position of Vice-Chief Naval General Staff, and command of the Japanese fleet in Chinese waters, which he held at the time of Pearl Harbor. Koga reached the top of the ladder in April, 1943, when he was appointed CinC Combined Fleet upon the death of Admiral Yamamoto.
Koga was to replace a colorful and popular figure. There could be only one Yamamoto as far as the Japanese were concerned, and to them his death was an irreparable loss. Even though Koga was considered the next best qualified officer in the Imperial Navy, it was difficult then, as always, to take up where a national hero left off. Koga faced a discouraging prospect, for no matter what he did he would always be overshadowed by the great Yamamoto who commanded in the hour of victory, and who passed away before the time of defeat. Koga believed, as had Yamamoto, that Japan’s only chance of saving its empire was to win out in a major fleet action, before the vastly superior American production and the gradual attrition of Japanese strength would make the loss of the war inevitable. Yamamoto had a chance of achieving this grand strategic objective at Midway, before the loss of four carriers ruined his opportunity. Now time was running out, Yamamoto was dead, and the fate of the Imperial Navy was entrusted to his less colorful but able and determined successor.
Koga believed that the American Navy would give him his chance for a decisive engagement by advancing a large fleet from Pearl Harbor towards the Mandates. Koga’s Chief of Staff, Vice-Admiral Shigeru Fukudome, described Koga’s strategy as “ . . . not a plan to draw the American fleet into a decisive action, but rather to wait until the American fleet came up; and he felt sure that they were bound to come up if he only waited.” Meanwhile, Koga intended to keep the main strength of his fleet intact at Truk and ready to crush the American fleet when it advanced from Hawaii. By September the Truk-based striking force included elements of the First, Second, and Third Fleets, as follows:
ADMIRAL KOGA’S STRIKING FORCE
First Fleet
Batdiv 1: Musashi, Yamato
Batdiv 2: Nagato, Fuso
Second Fleet
Crudiv 4: Takao, Chokai, Maya, Atago
Crudiv 5: Myoko, Haguro
Desron 2: Light cruiser Noshiro and 7 destroyers
Third Fleet
Cardiv 1: CV’s Skokaku, Zuikaku, CVL Zuiho (185 planes)
Batdiv 3: Kongo, Haruna
Crudiv 7: Kumano, Suzuya, Mogami
Crudiv 8: Tone, Chikuma
Desron 10: Light cruiser Agano and 6 destroyers
Light cruiser Oyodo
Altogether Koga’s force came to 3 carriers, 6 battleships, 11 heavy cruisers, 3 light cruisers and the destroyers. Actually there were never more than 7 or 8 heavy cruisers available for the striking force at any one time, since two were usually at Rabaul and one or two in drydock. These ships were the cream of the Imperial Navy. The other battleships and cruisers were older and slower. Scattered from Hokkaido to Singapore, they were engaged in the unglamorous duties of training, escort, and supply. The best of the remaining carriers had only training squadrons aboard. The rest were too slow for fleet operations and were ferrying planes from the homeland to forward bases.
Koga was confident that, if he kept his striking force together and waited patiently, the American fleet would move west and provide him with the opportunity to strike hard with his concentrated forces. The concentration of his forces was the core of Koga’s strategy. The more he dispersed his strength, the less force he could bring to bear in a decisive engagement. Therefore Koga was determined to do all in his power to keep his Truk-based fleet intact. There were two factors that threatened this policy.
The first threat to Koga’s plans came from Imperial General Headquarters itself. In May Koga went up to Tokyo to discuss his strategy at Imperial GHQ, and his views were challenged by arguments advocating a more defensive deployment of naval forces. Koga won this battle, however, and his plan to seek a grand engagement was incorporated into the overall strategic policy of Imperial GHQ. The second threat to Koga’s plans was the deterioration of the Japanese position in the Rabaul area in the face of American advances in New Guinea and the Solomons. The threat to Koga lay in the high rate of aircraft attrition at Rabaul. Sending plane reinforcements there was like pouring sand down a rat hole. Nevertheless, reinforcements had to be sent, and were, but there never seemed to be enough. Often the only available planes were in the carrier divisions. The Combined Fleet was always loathe to commit its carrier planes and their scarce highly-trained pilots at Rabaul. Both were in short supply, and were sent to Rabaul only when a situation arose that seemed to favor the mass employment of land-based aircraft. In April Yamamoto based a part of his carrier plane force at Rabaul for 17 days, sustaining high losses. Koga succumbed to temptation and tried the same thing in August with further losses. The result of both expeditions was the reduction of Cardiv 2 (Junyo, Hiyo, Ryuho) to the status of a training force, so that by September the only effective carrier planes available were the 185 in Cardiv 1. Despite the sacrifice of Cardiv 2 the plane shortage at Rabaul continued acute and carrier aircraft reinforcements were as much in demand as ever. Moreover, carrier pilots who engaged in the April and August operations at Rabaul grossly exaggerated the number of vessels they had sunk and damaged, so that both Koga and Imperial GHQ were led to overestimate the effectiveness of basing carrier planes at Rabaul.
Thus by September Koga was torn between two courses. If he adhered to his original plan of keeping his Truk-based force intact and in readiness for a major engagement, he might be missing favorable opportunities of inflicting great damage on Allied shipping in the Rabaul area. On the other hand, if he should send carrier aircraft to Rabaul for a third time, any resultant losses would weaken his force at Truk and lessen its chances of winning against the American fleet that he expected to advance from the east. If the Japanese had had enough planes to go around, this dilemma might not have arisen. As it was, they had a one front air force fighting a two front war in the Central Pacific. The threat to Koga’s strategy lay in the fact that the need for his carrier aircraft appeared more immediate and urgent at Rabaul than at Truk. Toward the end of 1943 Imperial GHQ began to advocate the employment of Cardiv 1 at Rabaul, but Koga determined to keep his planes at Truk as long as he could.
Koga expected the American fleet to advance from Pearl Harbor to the Wake-Marshalls area. He hoped to gain intelligence of the advance not only by radio interception, but by reconnaissance of Pearl Harbor itself. On September 4 Koga ordered submarine I-36 to move from Yokosuka to Hawaiian waters. There it was to dispatch its small scout plane over Pearl Harbor in a series of three reconnaissance missions scheduled to take place at night on or about September 21, October 8 and October 20. (All dates in Tokyo time unless otherwise noted.) Actually only the third mission was performed. Upon receiving some indication that an American fleet was on its way, Koga planned to move his striking force from Truk to Eniwetok. At Eniwetok he would not be far from the American fleet when it entered, as he expected it would, the Wake-Marshalls area. Then would come the major engagement that was the object of his strategy. Koga would have the advantage of being close to friendly bases and could utilize land- based aircraft from Wake or the Marshalls.
The fleet at Truk was kept in top condition. An intensive training program included frequent firing practice and special training for night and dawn combat, culminating in a “dry run” sortie to Eniwetok. On September 17 the following units completed preparations for leaving Truk, and departed for Eniwetok at 2130 on the following day.
FORCES ENGAGED IN THE SEPTEMBER SORTIE:
TRUK-ENIWETOK-TRUK:
SEPT. 18-25, 1943
Second Fleet
Crudiv 4: Takao, Alago
Crudiv 5: Myoko, Haguro
Desron 2: Light cruiser Noshiro and destroyers
Third Fleet
Cardiv 1: CV’s Shokaku, Zuikaku, CVL Zuiho (185 planes)
Batdiv 3: Kongo, Haruna
Crudiv 7: Mogami
Crudiv 8: Chikuma
Desron 10: Light cruiser Agano and destroyers
Light cruiser Oyodo
The expedition was commanded by Vice- Admiral Takeo Kurita, CinC 2d Fleet. Koga himself remained at Truk with the four battleships of the First Fleet. The two faster Kongo-class battle wagons were included in the line-up. Four of the heavy cruisers did not participate. Kumano was in drydock at Kure, Maya and Suzuya were temporarily assigned to the Rabaul area, and Chokai, just out of drydock, was engaged in convoy duty.
Although Japanese records describe this as a training cruise, the expedition may have been Koga’s response to information regarding the movement of Rear-Admiral Pownall’s Task Force 51 towards the Gilbert Islands. Evening of the 19th saw 18 B-24’s from Canton and Funafuti raiding the Tarawa airstrip. Next morning planes from Task Force 51, including carriers Belleau Wood, Princeton, and Lexington gave Tarawa a thorough going over, followed by more B-24’s on a reconnaissance and final bombardment mission. This strike succeeded in knocking the Tarawa airstrip out of the war, for the Japanese never again based planes there. Morning of the 20th, when news of the strike reached the Japanese fleet then heading for Eniwetok, the training operation was immediately suspended, and the alerted fleet reached Eniwetok at 1440. There it stayed until the 23d, when, convinced that the American fleet was going to stay out of reach, it left at 0900 and arrived Truk at 1440 two days later. Thus ended the September sortie. An American task force had struck from the east as Koga expected, but its arrival and departure found the Japanese striking force over 800 miles away.
Meanwhile, the position of the Japanese in the Rabaul area was rapidly deteriorating. New Georgia in the Central Solomons was in American hands by the end of August, and in the following month Allied forces advanced up the New Guinea coast, taking Salamaua and Lae. Newly won airfields were quickly put to use, and American planes were on the way to achieving control of the air over Rabaul.
Up to this time Imperial GHQ had some hopes of being able to hold out in the Rabaul area and in the Marshalls, but in mid- September it was decided that these areas could not be held permanently, and a new policy called for a line of last ditch defense running from the Banda Sea through the Carolines. In order to gain time to strengthen this line, Imperial GHQ decided to put up a firm resistance in the Solomons, New Guinea, and in the Gilberts-Marshalls. The Japanese were resigned -to losing these areas eventually, but hoped to make their conquest so costly that by the time the Americans reached the Banda Sea-Carolines line, the balance of strength in the Pacific would swing in favor of Japan. Koga’s striking force was to play an important part in realizing these twin objectives of delay and attrition. He was to make every effort to deal a decisive blow to the enemy’s surface forces in order to slow down the American schedule of advance. However, while the new September policy of Imperial GHQ accepted Koga’s strategy of seeking a major engagement, it also threatened the integrity of the striking force that Koga was trying to keep together for that engagement. At the end of the month Imperial GHQ called for a series of strong local delaying actions in the Rabaul area, to be supported by a third concentration of carrier aircraft at Rabaul. Known as the RO Operation, this plan called for the planes of Cardiv 1 to leave their carriers at Truk and fly down to Rabaul, where they would cooperate with local air strength to deliver a smashing blow to Allied shipping off New Guinea. The operation was intended for the middle of October, but the exact timing was left to Koga.
Matters had come to a head. Koga saw clearly that activation of the RO Operation would hamstring his striking force, which would be crippled without its air arm, so that any major engagement would be temporarily impossible. Moreover, if Cardiv 1 suffered the fate of Cardiv 2, his cherished hope of a decisive engagement would have to be postponed for at least six months until a new carrier plane force could be assembled and trained. Thus it is not surprising that although Imperial GHQ had intended the RO Operation for the middle of October, Koga delayed its activation in favor of a final attempt to engage the American fleet while his striking force was still intact.
The American carrier strike against Wake on October 6 took Koga by surprise. When he received news of the raid he put his striking force on the alert and prepared to leave Truk, but nothing came of it, and he cancelled the alert on the 8th. No report was received from I-36 at this time, but in a few days radio intelligence indicated the possibility of another American strike in the Wake-Marshalls area. Koga thought his chance had finally come. He put his fleet in readiness to sail by the 16th, ordered I-36 to scout Pearl Harbor, and at 0940, October 17, left Truk with his fleet on a second sortie to Eniwetok.
FORCES ENGAGED IN THE OCTOBER SORTIE:
TRUK-ENIWETOK-TRUK:
OCT. 17-26, 1943
First Fleet
Batdiv 1: Musashi, Yamato
Batdiv 2: Nagalo, Fuso
Second Fleet
Crudiv 4: Takao, Chokai, Maya, Atago
Desron 2: Light cruiser Noshiro and destroyers
Third Fleet
Cardiv 1: CV’s Shokaku, Zuikaku, CVL Zuiho (194 planes)
Batdiv 3: Kongo, Haruna
Crudiv 7: Siczuya, Mogami
Crudiv 8: Tone, Chikuma
Desron 10: Light cruiser Agano and destroyers
Light cruiser Oyodo
The October sortie force was stronger than the September expedition by four battleships and one heavy cruiser. Koga himself commanded from his flagship Musashi. The plane strength of Cardiv 1 was at a peak of 194, although some of this number probably stayed behind at Truk. Myoko and Haguro had replaced Maya and Suzuya at Rabaul, but Chokai went along this trip, raising the total of heavy cruisers to eight. Kumano was still in drydock.
Just after midnight on the morning of October 18 (Pearl Harbor time), a small Japanese monoplane was spotted off Barber’s Point, just five miles from Pearl Harbor. Caught in the beams of searchlights, the plane turned and darted out to sea, hugging the surface of the water. This was the scout plane dispatched from I-36, evidently making the first attempt to accomplish her mission. Although U. S. Naval authorities stated their belief that the plane failed to gain any important intelligence, and although the plane disappeared before reaching I-36, the submarine reported four carriers, four battleships, five cruisers and seventeen destroyers at Hawaii. From this report, Koga concluded that the missing elements of the American fleet had already begun operations against the areas mentioned in his radio intelligence—Wake or the Marshalls. Since the reconnaissance occurred at about 2100 on the 19th Tokyo time, Koga received the report after his arrival at Eniwetok at 0630 the same day.
The fleet waited at Eniwetok for several days with no sign of the expected enemy task force. But Koga refused to give up. At 0430 October 23 he moved his fleet from Eniwetok to a point 250 miles southwest of Wake and conducted air searches over the ocean to the northeast of that island, with still no sign of an American force. By this time Koga realized that he had been misled by the report of I-36. Actually the American fleet had been at Pearl all along. At this point Koga abandoned all hope of an engagement and turned his fleet back towards Truk, arriving October 26. Two days later he took the fatal step that would break up his striking force, and activated the RO Operation. 173 planes from Cardiv 1 were to cooperate with about 200 planes of the 11th Air Fleet, already stationed at Rabaul. Koga’s planes left their carriers at Truk and flew south to Rabaul, completing their advance by November 1. Light cruiser Aganoy probably with some destroyers, was also sent down and arrived on the same day.
While Koga was off on the October sortie, intensified American air strikes against Buin, Ballale, and Rabaul indicated that the Allies were planning a new operation in the area. On the 27th the Americans landed in the Treasury Islands, and on November 1 the 3rd Division, U. S. Marines hit the beach at Empress Augusta Bay on Bougainville, only 225 miles from Rabaul itself. The Americans had declined to oblige Koga by advancing from the east, but here was a made-to-order target within easy reach of Rabaul. Koga immediately shifted the target of the RO Operation from the New Guinea coast to Admiral Halsey’s forces off the Bougainville beachhead. But that was not enough! Koga had waited in vain for two months to engage the elusive task forces from Pearl. Now he had a target tied down to a beachhead in easy reach of Rabaul, and he would wait no longer. He determined to strike with the two heavy cruisers at Rabaul and seven more that he would send down from Truk. The local naval headquarters at Rabaul made strong protests against the use of surface units in the waters south of New Britain, for these waters were now dominated by enemy aircraft. But Koga was adamant. This was the best chance he had had in months, and he was not going to let it escape.
Instead of waiting for the seven heavy cruisers to reach Rabaul, Koga ordered the smaller Rabaul-based force to attack the beachhead at once. Heavy cruisers Myoko and Haguro, previously detached from Koga’s striking force, with light cruisers Agano and Sendai and six destroyers steamed out of Rabaul for Empress Augusta Bay to attack the transports off the beachhead and land reinforcements. They were intercepted by the cruisers and destroyers of Admiral Merrill’s Task Force 39 with disastrous results. Sendai went to the bottom and the two heavies suffered considerable damage. After withdrawing to Rabaul, Myoko and Haguro left for Truk on the 4th, and later entered drydock at Sasebo, where they remained until the middle of December. Two of Koga’s eleven heavy cruisers were knocked out. The score was two down and nine to go.
On November 3 Koga’s hurriedly organized heavy cruiser task force left Truk under the command of Vice-Admiral Kurita, CinC Second Fleet. Except for Chokai, which turned back to escort two damaged tankers, all arrived at Rabaul on the 5th.
HEAVY CRUISER TASK FORCE:
TRUK-RAB A UL-TRUK:
NOV. 1943
Crudiv 4: Takao, Chokai, Maya, Atago
Crudiv 7: Suzuya, Mogami
Crudiv 8: Chikuma
Desron 2: Light cruiser Noshiro and 6 destroyers
But Kurita’s force had been spotted by a B-24 on the way down, and this advance notice led to the famous Rabaul carrier strike of November 5. Planes from Princeton and Saratoga caught the Japanese cruisers in Simpson Harbor, Rabaul, on the afternoon of that day in a surprise attack which took the fight out of the Japanese heavies. Four were badly damaged. Three of the cripples, Takao, Atago, and Mogarni left for Truk at once, escorted by Chikuma and Suzuya, both still operational. Takao and Atago would be in drydock in January, and Mogami until February. Maya, with a bomb down a stack, was too badly damaged to move, and remained at Rabaul for emergency repairs. Six down and five to go.
Light cruisers Noshiro, Agano, and Yubari remained at Rabaul to keep the battered Maya company until November 11, when a second Rabaul carrier strike hit hard at this force. On that very day all but Yubari left for Truk, where Agano underwent repairs until December 14. Noshiro remained operational, and the third light cruiser in Koga’s striking force, Oyodo, had been at Truk all along. Maya, after further patching at Truk, entered drydock at Yokosuka and remained there until March. Meanwhile, Kumano had finished her long stay in drydock and reached Truk on the 8th, but Tone entered drydock a few days earlier for a routine check, which accounts for her absence from the heavy cruiser task force. Thus by the middle of November, seven of Koga’s eleven heavy cruisers were undergoing repairs, and none would emerge from drydock before the middle of December. Kumano, Chokai, Chikuma and Suzuya were the only operational heavies left.
Meanwhile Cardiv 1 engaged in fierce attacks against Allied vessels in the Solomons. Day by day the carrier planes suffered increasing losses that could only be justified by the exaggerated successes reported by their pilots. By the 10th, only 100 of the original 173 remained operational, and these were further reduced the next day in a savage battle above the Solomon Sea, when the total losses reached 121. A dozen planes a day was too great a price for the privilege of remaining at Rabaul! Cardiv 1 was the last operational carrier division in the Japanese navy. Eighty-six of the 192 highly-trained pilots and crew members had also been lost. A few more days at this rate and Cardiv 1 would not even have a skeleton force around which to rebuild. On the 12th Koga ordered a withdrawal, and on the 13th the remaining 52 planes took off for Truk to rejoin their carriers. Thus within a few brief days the air arm of Koga’s striking force was all but annihilated.
Two weeks after Koga began dribbling his forces down to Rabaul the striking force that he had hoarded so carefully at Truk for a major engagement had been rendered ineffective for that purpose. While the reduction of his heavy cruiser force was bad enough, the decimation of his carrier planes was disastrous, for without them he would not dare commit the remaining cruisers, and certainly not the battleships, in a major engagement. All the situation needed was a touch of irony, and that was not long in coming. On November 21 United States Marine and Army forces invaded Tarawa and Makin in the Gilberts. The supporting fleet units were organized into two attack forces, one for each atoll, and a powerful fast carrier force to protect the operation from interference by the Japanese fleet. Here at last was Koga’s target. Although the American fleet did not present itself in the Wake-Marshalls area, it had moved towards Koga from the east, it was tied down to an amphibious operation, and could be attacked by Japanese land-based aircraft in the Marshalls. If the invasion of the Gilberts had come three weeks earlier, if Koga had kept his striking force intact instead of sending it off piecemeal to Rabaul, if Koga could move to the Gilberts in November the same force he moved to Eniwetok in October—well, speculation is always interesting! Even if Koga had kept his striking force intact, he would have to face an American fleet including five fast battleships, seven old battleships, seventeen carriers (six CV’s, five CVL’s, six CVE’s), eleven heavy cruisers, and a host of supporting vessels. As things turned out, Koga did not keep his striking force intact and he could not seize the opportunity for a decisive engagement when it arrived. As far as the main object of his strategy was concerned, the admiral had lost his fleet.
Koga tried to pick up the pieces as best he could. Thirty-two fighters from his carrier divisions (Cardiv 1 and/or Cardiv 2) were sent to the Marshalls where they arrived on the 25th, too little and too late to be much help. The four remaining heavy cruisers and light cruiser Noshiro were dispatched to Kwajalein to escort a counterlanding operation designed to transport 1,500 reinforcements to Tarawa. Chikuma, at Eniwetok on the 21st (D-Day), advanced to Kwajalein by the 23d. On the 24th Chokai, Suzuya, Kumano and Noshiro left Truk and arrived Kwajalein the 26th. Here they rendezvoused with three light cruisers carrying the reinforcements; by this time the Gilberts were securely in American hands. But the Japanese still refused to give up hope. On the 27th the escort force left Kwajalein for Eniwetok to escape an anticipated American air raid. After refueling they returned to Kwajalein to rejoin the troopbearing light cruisers, but by this time the operation was obviously out of the question. The reinforcements were discharged at Mille, and the force left for Truk on December 3.
Koga’s misfortunes may be aptly summed up in the words of his Chief of Staff, Vice-Admiral Fukudome:
Admiral Koga’s idea was to save up his full strength for one decisive engagement. That was the reason why he disregarded the constant request for air reinforcement from Rabaul, because the only planes that could be sent were carrier planes. But in November, as Bougainville landing operations commenced, he was forced to send his air strength to Rabaul. As it turned out, practically all of them were lost at Rabaul and Bougainville. Consequently the fleet air strength was almost completely lost, and although the Gilbert fight appeared to be the last chance for a decisive fight, the fact that the fleet’s air strength had been so badly depleted enabled us to send only very small air support to Tarawa and Makin. The almost complete loss of carrier planes was a mortal blow to the fleet since it would require six months for replacement, and it was felt that it would take until May or June of 1944 to complete that replacement. In the interim, any fighting with carrier force was rendered impossible.
Koga felt his failure deeply, taking it as a personal disgrace. He often expressed his envy of Yamamoto’s good fortune in meeting death at the right time, with the taste of victory still on his lips. The tradition of Koga’s samurai clan was that a fighter should select the time and place of his death, and the earlier in battle the better. Koga now determined to make his last stand at the Banda Sea-Carolines line, and to die in its defense. He would not have long to wait.
During the first two months of 1944 the American advance carried beyond the Gilberts to Kwajalein-Roi, Majuro and Eniwetok in the Marshalls. Both Rabaul and Truk were rendered ineffective as fleet bases, and the main elements of the Imperial Navy retreated to the homeland and the Singapore area to recuperate from the November debacle. The recovery was slow, and the Japanese and American fleets did not meet in a major engagement until June, with the assault on Saipan and the Battle of the Philippine Sea. Koga would not live to see it. In the face of the American advance Koga moved his headquarters to Palau and concentrated his energies on plans for the defense of the Banda Sea-Carolines line. On March 31 he boarded a flying boat and took off for Davao, but his plane, flying through bad weather, was never heard from again. So ended the career of the Imperial Navy’s second-best officer.