Kantai kessen

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The Decisive Battle Doctrine (艦隊決戦, Kantai Kessen^?) was a naval strategy adopted by the Imperial Japanese Navy following the Russo-Japanese War. It called on the use of a strong battleship force, which would destroy an invading fleet as it approached Japan after suffering losses through attrition as it penetrated Japanese perimeter defenses.

The decisive victory of the Japanese fleet over the Imperial Russian Navy at the Battle of Tsushima in the Russo-Japanese War had validated the doctrine in the eyes of the Imperial Japanese Navy General Staff, and future naval procurement and deployed was centered around refinements of the “decisive victory”, or kantai kessen doctrine.

Opposition to this doctrine grew in the 1930s, as advocates of the new submarine and naval aviation technologies foresaw that the concept of the line of battle between opposing battleships fleets had been rendered obsolete (Evans 1997). However, conservative supporters of kantai kessen, such as Admiral Osami Nagano, dominated within the senior staff of the Japanese Navy and the kantai kessen concept remained the primary Japanese naval strategy into the Pacific War.

Contents 1 Background 2 Battle Plan 3 Flaws 4 Opposition 5 In Practice 6 References 7 Notes

[edit] Background

The senior officer class of the Imperial Japanese Navy was heavily influenced by the works of Alfred Thayer Mahan, whose works (including The Influence of Seapower Upon History,1660-1783, published in 1890) were required reading at the Imperial Japanese Naval Academy and Naval Staff College. ^[1]

Mahan believed that control of seaborne commerce was critical to domination in war. If one combatant could manage to deny the use of the sea to the other, the others' economy would inevitably collapse, leading to victory. Mahan's theory relied on the use of a fleet of battleships to establish command of the sea. The Mahanian objective was to build a fleet capable of destroying the enemy's main force in a single decisive battle. After this victory was won, it would be easy to enforce a blockade against the enemy. For the weaker combatant, the goal was to delay such a climactic battle for as long as possible. While their fleet still posed any threat, the enemy could not risk splitting their forces to close off trade routes. This led to the strategy of a fleet in being, a naval force kept deliberately in port to threaten rather than act. Mahan's doctrines were adopted by a number of navies, notably the Royal Navy and contributed to types of capital ships produced in the final years of the 19th and early years of the 20th century.

In the 1907 Imperial National Defense Policy, the shift of Japan's military focus shifted away from the defeated Imperial Russia and towards the United States as the primary threat to Japan's future security. In Japanese minds, the United States had proven to be an aggressive expansionist power in Asia, with its overthrow and annexation of the Kingdom of Hawaii and suppression and colonization of the Republic of the Philippines. The Open Door Policy towards China was in conflict with Japanese aspirations on the Asian mainland, and its racist immigration policies indicated potential American racial enmity towards the Japanese. Furthermore, the United States Navy had recently surpassed the United Kingdom's Royal Navy as the largest and most powerful fleet in the world.

Based on a theoretical United States Navy strength of 25 battleships and heavy cruisers, Japanese naval theoreticians led by Admiral Satō Tetsutarō postulated that Japan would need a fleet of at least eight first-line battleships and eight cruisers for parity. When Naval Minister Admiral Yamamoto Gonnohyoe presented the budget request for this Eight-eight fleet to the Diet of Japan, the amount was more than twice that of the entire Japanese national budget at the time. Budget limitations meant that a large percentage of naval procurement was allotted to battleships to complete the Eight-eight Fleet project, at the expense of other types of warships and new technologies.

[edit] Battle Plan

The kantai kessen strategy presumed a defensive posture by the Japanese Navy, with the bulk of its battleship fleet in strategic reserve, as secondary forces based on cruisers and destroyers waged a campaign of attrition against the American offensives ^[2]. As with the Russian Baltic Fleet in the Russo-Japanese War, the American fleet would need to be drawn out to a long distance away from its source of supplies, and destroyed in a climatic final battle similar to the Battle of Tsushima ^[3].

Up until the 1920s the Japanese expected this decisive battle to occur near the Ryukyu Islands and for the battle to be “a defense of Japan's home waters conducted purely by surface forces.” However, as technology increased the ranges of submarines and aircraft, the projected location of the battle moved further and further eastward. By 1940, the Japanese were planning for the decisive battle to be fought “somewhere east of a line between the Bonin and Mariana Islands.” ^[4].

The Japanese defensive posture was considerably enhanced by the acquisition of the South Pacific Mandate from the League of Nations after World War I. The Pacific islands (the Caroline islands, Marshall islands, Mariana Islands and Palau were heavily fortified to become “unsinkable aircraft carriers”, from which Japanese forces could sortie to inflict damage on any approaching fleet. The Japanese counted on these island outposts to wear down the approaching American fleet to a level to near parity where the Japanese Combined Fleet could meet them, and crush them in a decisive battle. ^[5]

According to the first stage of the battle plan, fast attack submarines would first be used to weaken the American fleet by 10%, then Japanese bombers from land bases and aircraft carriers would inflict another 10% casualty rate. Fast attack battleships and heavy cruisers would then strike enemy screening formations allowing massed light cruiser and destroyer raids with long-distance torpedoes, while air strikes launched from the Japanese carriers would neutralize the American carrier fleet. According to plan, this moment would be the “decisive” stage of the decisive battle, when the battleships of the Combined Fleet, including the modern Yamato class, would join the battle. Finally, the older battleships would join the fray and mop up the surviving remnants of the American fleet ^[6].

[edit] Flaws

Mahan's premise that a reserve force would be incapable to recover after an initial overwhelming defeat was refuted by the US Navy's own recovery after the attack on Pearl Harbor. The Japanese pursuit of the "decisive battle" was carried out to such an extent that it contributed to Japan's defeat in 1945.^[7][8]

Japanese planners refused to abandon the kantai kessen doctrine, even after the Battle of Midway, which proved that decisive battles fought between fleets of battleships had become obsolete by the development of submarines and aircraft carriers.^[9]

As Japan lost ground in the Pacific, Japanese naval planners continued to rely on the Americans to attempt to take every Japanese island outpost along the way to Japan. However, the Americans had already decided on a strategy of “island hopping” in the Pacific, ^[10] whereby the Americans bypassed islands not of strategic value, providing the Japanese fewer opportunities to wear down the American forces before the decisive battle. In addition, since Japanese forces had to spread thin in order to defend against many possible American invasions, the Americans had the initiative and were numerically superior to the Japanese at nearly every engagement.

In addition, the Japanese submarine force was not as effective as planned, and there was little hope of the submarine arm of the navy inflicting a 10% casualty rate on the American fleet ^[11]. Despite being one of the first countries to build aircraft carriers and a naval aviation arm, conservatives within the navy refused to accept naval aviation as anything more than reconnaissance and artillery spotting for the battleship fleet. As a result, the Japanese equipped their fleet with the weapons to win a battle that they would likely never fight, putting them at an enormous disadvantage in the battles they did fight.

The Japanese investment in battleships also meant other branches of the fleet, particularly destroyer escorts used to protect shipping, were neglected ^[12]. As a result, the Japanese suffered substantial losses in shipping to American submarines, resulting in an enormous strain for resources for the Japanese war machine.

On the other hand, Japan's success at Pearl Harbor conversely forced the American navy to take steps towards establishing the world's first carrier-based naval doctrine. (Lowe 2005). The American superiority in aircraft carriers played a large role in the Battle of Midway, and American air superiority in the Pacific eventually doomed the Japanese in later battles. Where deployed, the Japanese battleships proved extremely vulnerable to air attack.

[edit] Opposition

Admiral Isoroku Yamamoto led the opposition to the kantai kessen doctrine in the Japanese navy. Contrary to other naval officers, Yamamoto claimed that building huge battleships such as Yamato and Musashi was pointless, as that no ship was unsinkable, saying “The fiercest serpent may be overcome by a swarm of ants”^[13]. According to Yamamoto, carrier-based airplanes would be the deadly swarm of ants in the new war. He believed it unlikely the Japanese and American navies would ever engage in a battleship engagement. Instead, he believed the struggle in the Pacific would be for control of the skies as naval aviation can project firepower to much greater distances than battleships. However, Yamamoto was killed on April 18, 1943, and with his death came the death of the staunchest advocate of naval aviation in the Japanese navy.

As the war progressed, other officers came to question other aspects of the Kantai Kessen Doctrine; for example, Admiral Matome Ugaki asked, “I wonder why they don't give enough consideration to attacking enemy elements easy to destroy, instead of always seeking a decisive battle?” ^[14]. Instead of seeking one ultimate naval encounter, Ugaki advocated smaller engagements of concentrated forces to pick off weak elements of the American navy instead of attempting to destroy the entire fleet at once.

[edit] In Practice

The naval battles of the Coral Sea and Midway represented a departures from the traditional doctrine of kantai kessen ^[15]. Planned by Yamamoto, these battles aimed at achieving decisive victories to knock the American fleet out of the war at an early stage. However, failure to secure a decisive victory at the Coral Sea, and the disastrous defeat at the Battle of Midway ended Yamamoto's plans for an aggressive, offensive strategy. Rather than reorganize the fleet around three carrier groups similar to the USN Task Forces, as had been argued by Vice Admiral Tamon Yamaguchi even before Midway, the Japanese Navy General Staff refused to accept the subordination of battleships to aircraft carriers and reverted to the more conservative defensive strategy within the doctrine of kantai kessen ^[16]

For most of 1943, Japan focused on preparing perimeter defenses to stand up to the coming American offensives. The Japanese defensive perimeter was such that the Marshall Islands and Gilbert Islands were left outside of the area to which the Japanese were willing to commit the Combined Fleet to defend. The Americans thus took these two island groups without significant resistance from the Combined Fleet ^[17]

After the capture of the Marshalls in early 1944, the Japanese sought the decisive victory in the Marianas ^[18]. Contrary to the Marshall Islands, the Japanese deemed the Marianas vital enough to commit the Combined Fleet. In the Battle of the Philippine Sea, also known as the “Great Marianas Turkey Shoot,” the Japanese lost over 400 aircraft and three of nine aircraft carriers, effectively crushing the Japanese carrier force in the Pacific ^[19]. While the Japanese plans had intended for the American fleet to gradually be ground down during the American offensives across the Pacific, in actuality it was the Japanese Fleet which lost irreplaceable aircraft carriers, planes, and pilots, reducing their ability to win any battle, let alone a decisive battle against the American fleet. However, the Japanese did not alter their strategy and made one last great attempt to achieve a decisive naval victory during the defense of the Philippines.

The Japanese knew that in order to continue the war, the Philippines needed to be held against American invasion. If the Philippines were to fall, then Japanese supply lines to the oil fields of Southeast Asia would be severed and Japan's fleet and industries would be unable to continue the war ^[20]. Therefore, the Japanese committed the entire Combined Fleet, despite lack of sufficient air support, in a last desperate attempt for a decisive victory. Beginning October 24, 1944, the fleets engaged in the Battle of Leyte Gulf, one of the largest naval battles in history. The battle was a decisive battle, but with Japanese on the losing end, as the bulk of the remaining combat effective force of the Combined Fleet annihilated in the Battle of Leyte Gulf, and the Imperial Japanese Navy unable to recover afterwards ^[21]

In the end, the Japanese search for a decisive battle which to turn the course of the war based on a battleship–to-battleship combat was futile since the American carriers refused to allow the Japanese battleships to get within range. The decisive battle was indeed fought, but not with battleships as envisioned under the kantai kessen, but with naval aviation.

[edit] References

• Breyer, Siegfried (2002). Battleships and Battle Cruisers, 1905-1970: Historical Development of the Capital Ship. Doubleday & Company. ISBN 0385072473. 
• Costello, John T (1991 ed). The Pacific War: 1941-1945. HarperCollins Publishers Inc. ISBN 0892562064. 
• Evans　, David (1979). Kaigun: Strategy, Tactics, and Technology in the Imperial Japanese Navy, 1887-1941. US Naval Institute Press. ISBN 0-87021-192-7. 
• Gow, Ian (2004). Military Intervention in Pre-War Japanese Politics: Admiral Kato Kanji and the Washington System'. RoutledgeCurzon. ISBN 0700713158. 
• Healy, Mark (1994). Midway 1942: Turning Point in the Pacific. Osprey Publishing. ISBN 1855323354. 
• Lowe, Robert. "The Height of Folly: The Battles of Coral Sea and Midway." In The Pacific War Companion, by Daniel Marston, 75-105. New York: Osprey Publishing, 2005.
• Miller, Edward (1991 ed). War Plan Orange: The US strategy to beat Japan 1897-1945. US Naval Institute Press. ISBN 1591145007. 
• Thomas, Evan (2007 reprint ed). Sea of Thunder: Four Commanders and the Last Great Naval Campaign. Simon & Schuster. ISBN 0743252225. 
• Willmont, H. P. "After Midway: Japanese Naval Strategy 1942-45." In The Pacific War Companion, by Daniel Marston, 177-191. New York: Osprey Publishing, 2005.

[edit] Notes