The first book in the Fleet series, Japanese Combined Fleet 1941-42, examined the Imperial Japanese Navy (IJN) during the first six months of the war. During this period, the IJN enjoyed an unrivaled string of successes until May 1942. In the battle of the Coral Sea, the Combined Fleet fought its first battle against strong Allied forces and suffered a tactical and strategic defeat. This set the stage for the Battle for Midway, fought 4–6 June 1942. In what is (incorrectly) viewed as the single most decisive battle of the Pacific War, the Combined Fleet’s Striking Force suffered the loss of four fleet carriers. Since Japan began the war with only six fleet carriers, this had the effect of blunting the IJN’s offensive power. Before the Japanese could react to this new dynamic, the United States Navy (USN) grabbed the initiative in the Pacific and launched an offensive at Guadalcanal in the southern Solomon Islands.

Japanese Combined Fleet 1942–1943 covers the period between August 1942 and November 1943, and begins with the first American offensive of World War II. This landing on Guadalcanal prompted a six-month grinding battle of attrition between August 1942 and February 1943 before the Japanese were forced to retreat from the island. During this contest, the IJN suffered heavy losses in aircraft, aircrew, and ships. In the ensuing campaign for the Central and Northern Solomons, the IJN was forced into a force preservation mode. Not until November 1943 did the then commander of the Combined Fleet, Admiral Koga Mineichi, decide it was necessary to commit major fleet units and precious carrier aircraft to defend Bougainville in the Northern Solomons. This book details how the Combined Fleet fought the Guadalcanal and Solomons campaigns and examines why these were so critical for Japanese naval fortunes for the remainder of the war.
Even after the Midway debacle, on 1 August 1942, just before the start of the Guadalcanal campaign, the Combined Fleet held a slight numerical edge over the USN in the Pacific. At the end of the Solomons campaign at the end of November 1943, the Combined Fleet was in a definite position of inferiority compared to the USN. During this time, the Combined Fleet had suffered heavy losses – one carrier, three battleships, three heavy and four light cruisers, 44 destroyers, and 33 submarines. In addition, it had lost the bulk of its highly trained aircrews. Furthermore, the Japanese failed to stop the American advance up the Solomons. Rabaul had been neutralized as a major base and the next phase of the war during which Japan’s inner defences were under threat was about to begin.

To a large degree, the IJN’s increasingly desperate straits were unavoidable. Japan was simply unable to replace the Combined Fleet’s losses, while American industrial capacity allowed the USN to not only replace its losses but to grow stronger each month.

Still, the Combined Fleet did not use its window of opportunity to stop the first USN offensive of the war before the disparity in industrial capacities between Japan and the United States made itself fully apparent. In August 1942, the Combined Fleet still enjoyed a quantitative and qualitative edge over the USN. The problem was Yamamoto’s failure to identify the struggle for Guadalcanal as a critical battle that Japan had to win to prove the viability of its defensive strategy. Failure to identify the importance of the battle translated into piecemeal commitment of forces to it. At no point during the six-month campaign did Yamamoto make an all-out commitment of the Combined Fleet’s remaining strength. The Americans did commit all available forces, and it was always just enough to defeat the latest Japanese attempt to retake the island.
Combined Fleet operations were not well designed during the campaign. The first example was the Japanese offensive in August. Mounting a major fleet operation to move a convoy of 1,500 troops to the island highlighted that the Japanese did not understand the dimensions of the campaign they were engaged in. While the Combined Fleet’s increased commitment in October gained it an important advantage by temporarily neutralizing the airfield and getting most of a convoy to the island, it was insufficient to gain victory. Even victory in the carrier battle of Santa Cruz was not sufficient to prevent the USN from maintaining its robust support of the American garrison on Guadalcanal. It was probably at this point that the Combined Fleet had its biggest advantage, but Yamamoto failed to seize the moment.

The next major effort in November was poorly synchronized and the result was catastrophic. Yamamoto resorted again to a battleship bombardment of the airfield, but again it was assigned to the least powerful battleships in the Combined Fleet. When the first bombardment failed on the night of 12/13 November, another attempt was ordered with only a single battleship. Incredibly, Yamamoto let the convoy advance toward Guadalcanal after the initial bombardment operation failed and before the second one could even be attempted. Aircraft from Henderson Field and from carrier Enterprise were able to attack the convoy, sinking six transports and forcing another back. After the second bombardment force was turned back on the night of 14/15 November, the American were able to finish the destruction of the convoy.

Yamamoto’s reluctance to commit his battleships in the waters off Guadalcanal was a key decision. Given the pivotal importance of Henderson Field and the demonstrated ability of Japanese battleships to badly damage it, an aggressive commitment of battleships could have turned the campaign. There are two major reasons for Yamamoto’s failure to do so. One was the orthodoxy of the Combined Fleet’s staff in terms of its thinking on the proper employment of battleships. These were capital units and were only committed if a decisive action was likely. Such ships could not be risked in the closed waters off Guadalcanal, especially at night. The other possible reason was a concern for the fuel requirements of such an operation.

Of course, the Japanese did employ battleships to bombard Henderson Field on three occasions. On all three occasions, Kongo-class units were employed. As the oldest battleships in the fleet, they were viewed as more expendable and their extensive pre-war training in night combat made them more suited and more survivable. The loss of Hiei to airpower from Henderson Field would seem to support Yamamoto’s reluctance to expose slower battleships to air attack. Given the relatively small scale of American air power at Henderson, which had difficulty sinking the previously damaged Hiei, the employment of the better protected Nagato class or even a Yamato-class superbattleship would have likely been effective in neutralizing the airfield and withstanding its counterattack. While the fuel factor was important, this author believes that this was an excuse. Sufficient fuel could have been found to send Yamato to Guadalcanal if her employment was expected to be decisive. The real failing was a lack of imagination. Without it, there was no way the Combined Fleet was going to risk its most impressive ships just to bombard an airfield.

So steep were losses at Guadalcanal that the ensuing Solomons campaign was conducted without any thought by Yamamoto or his successor to committing the main strength of the Combined Fleet. Yamamoto’s last offensive – Operation I – was a total failure. The days of simply massing air power against Allied targets to inflict significant blows in a single attack were gone. It is inconceivable that Yamamoto believed that only four attacks would render operational-level results by crippling Allied offensive power in the region. The operation was poorly planned and was marked by poor target selection, dispersal of effort, and lack of follow-up. The Japanese had yet to understand that to be effective air power must be applied in a concerted manner over time, not just in a few “decisive” raids. Operation I provided another example of Yamamoto’s inability to mass forces on the objective of operational importance.y

The Solomons campaign was a Japanese success at the strategic level since it took the Americans from February to November to advance the roughly 400nm from Guadalcanal to Bougainville. In this context, Japanese economy of force operations in the Central and Northern Solomons looked like a wise investment. At the operational level, the cost of the campaign was still high for the Japanese. The Combined Fleet’s destroyers took the lead in the Solomons campaign and suffered correspondingly heavy losses. For the remainder of the war, the Combined Fleet suffered a shortage of fleet destroyers. This was apparent during the major fleet actions in the Philippine Sea in June 1944 and in the Philippines in October 1944 when inadequate destroyer screens contributed to the heavy losses inflicted by American submarines on the Combined Fleet.

Another area of weakness was the Combined Fleet’s carrier-based air power. At the beginning of the Guadalcanal campaign, the carrier force was rebuilt following the Midway debacle. At this point, the overall quality of Japanese carrier air crews was still high. Victory at Santa Cruz was proof that Japanese carrier aircrews still possessed the determination and skills to inflict serious losses on the USN’s carrier force. However, in the face of continual losses, this changed dramatically by the end of the Solomons campaign. Even as the Combined Fleet decided to withhold the carrier air groups during the Solomons campaign, both Yamamoto and Koga relented at certain points and committed them hoping for decisive results. This failed to materialize, and more irreplaceable carrier aircrew veterans were lost. The downward trajectory of the quality of Japanese carrier aircrews was epitomized by the 173 aircraft sent to Rabaul on 1 November. On 2 November, 100 of these aircraft attacked the USN force which had just won the Battle of Empress Augusta Bay. Despite the force of four light cruisers and eight destroyers having no air cover for most of the action, the Japanese were only able to place two bomb hits on the stern of a light cruiser, causing little damage. On 11 November, the supposedly elite Japanese carrier aircrews mounted a major attack on an American carrier force of two fleet carriers and a light carrier attacking Rabaul. The Japanese attack force consisted of 27 dive-bombers and 14 torpedo planes with an escort of 67 Zeros. Twenty of the dive-bombers manged to attack the carriers; all three were near-missed by bombs, but none were hit. Only three dive-bombers survived the combined efforts of the defending American fighters and antiaircraft fire. The 14 torpedo planes followed next – all were shot down with no success. Since arriving at Rabaul on 1 November, the elite carrier air groups suffered the loss of 50 percent of their fighters, 85 percent of their dive-bombers, and 50 percent of their torpedo planes. Such losses had a dramatic effect. When later in November the USN launched an amphibious assault of the Gilbert Islands, the Combined Fleet’s carrier force was in no condition to respond. In fact, the carrier air groups would never recover. After being rebuilt by June 1944 in time for the decisive battle in the defense of the Marianas, the result was the near-total destruction of the Japanese carrier air groups in the largest carrier battle of the war.

In terms of the fundamentals of naval warfare, the Combined Fleet was unable to compete with the growing prowess of the USN. In the opening months of the Pacific War, and even into the first phase of the Guadalcanal campaign, the Combined Fleet possessed an excellent naval air arm with significant striking power against surface ships. By November 1943, Japanese naval air forces proved impotent against maritime targets. Japanese surface warfare capabilities were buoyed by impressive night fighting tactics. In the opening phases of the Guadalcanal campaign, the Combined Fleet could count on its night fighting skills to carry the day. This remained the case up until the end of the Guadalcanal campaign, except on some occasions where American tenacity or radar began to corrode the Combined Fleet’s night fighting edge. In the initial night battles in the Solomons campaign, the Americans failed to appreciate the full capabilities of the formidable Type 93 torpedo and paid dearly for this lack of insight. By the end of the campaign, the full incorporation of radar into American tactics and a new generation of aggressive leaders totally turned the tables on the Japanese at night. Though night battles were rare for the remainder of the war, when they occurred, the USN usually demonstrated its superiority.

As the Combined Fleet lost its edge in naval air power and night fighting, it also fell behind in other key areas. Japanese deficiencies in fleet air defense became more apparent and more costly as the weight of American air power increased throughout 1943. Japanese antisubmarine capabilities failed to keep pace with American technological advances on their submarines, operated with better tactics and by more aggressive submarine captains. In 1943, shipping losses were double that of new additions, reducing the size of Japan’s merchant fleet by almost one million tons. In 1944 merchant losses reached catastrophic proportions. Combined with the decline in warfare skills was a continuing negligence of intelligence and weakness in logistics. Whereas the Combined Fleet could still be considered superior to the USN in many areas in mid-1942, by the end of 1943 it could no longer compete with the USN in any warfare area. If 1943 was a year of rough parity, it led to a string of disasters in 1944 which marked the end of the Combined Fleet as an effective force.