After the Washington Treaty, the Japanese Navy's "88th Fleet" plan was shattered like a dream, and all new battleships and high-speed battlecruisers on the slipway and drawing board were canceled. After the Great Kanto Conference in 1923, the Japanese Navy reformulated its naval rearmament plan as a countermeasure to the Washington Conference. The plan is divided into plan A and plan B, and plan A that needs to be completed as a "current emergency policy" includes: 1. Complete the reconstruction of the two aircraft carriers Akagi and Kaga; 2. Construction of 4 Furutaka-class medium cruisers and 4 Myo-class large cruisers; 3. Ensure the construction of the hulls of 16 destroyers; 4. Construction of 4 cruiser submarines (large submarines, 18 submarine mines, and 18 fleet submarines (including 8 large submarine ships of the sea, whose construction was postponed due to the Washington Conference).
From this list, it can be seen that the Japanese Navy's countermeasure to the Washington Treaty is to build a large number of cruisers, destroyers, large submarines and other types of ships that are not limited in the treaty, and at the same time develop new long-range oxygen torpedoes, in order to give full play to the numerical superiority of these auxiliary warships and the advantages of torpedo warfare in the beginning of the war, and try to consume the American fleet before the decisive battle between the two fleets, so as to be able to defeat the US capital ships with the "** fleet" in the final fleet decisive battle. According to the statistics of the Japanese Navy's "Ari Final Association" in 1934, in the 10 years from the entry into force of the Washington Treaty to 1934, the Japanese Navy's "manufacturing cost" for the construction of capital ships was 71.23 million yen, and the "auxiliary ship manufacturing cost" for the construction of destroyers, submarines, submarine carriers and other auxiliary ships reached 778.26 million yen, which also reflected the development trend of the Japanese Navy during this period.
In 1926 and 1927, the Japanese Navy added two additional shipbuilding programs in order to increase the number of torpedo warfare forces in the ocean. The newly added ** construction plan includes 4 Kaohsiung-class cruisers, 24 snow-blowing destroyers, 1 additional cruiser submarine and 3 fleet submarines. The new shipbuilding program is called Plan B. On the eve of the 1930 London Naval Conference, Plan C was formed, which included the construction of 4 Kongo-class ships, 4 additional Kaohsiung-type cruisers and 24 Fuyuki-type destroyers, 4 additional cruiser submarines and 24 fleet submarines, and 1 additional large aircraft carrier.
With Plan C as the main body, the Japanese Navy formed the first supplementary plan of the 1932 year, the Plan, or "Maruichi Plan". After proposing the "nine-stage operation" strategy against the United States, the plan was supplemented in 1933, and the second supplementary plan for 1934-1935, the plan (Maruji Plan), included the construction of two Soryu-type aircraft carriers, four Mogami type cruisers, and Hatsuharu-type destroyers.
Since the end of the Russo-Japanese War, the Japanese Navy's idea of a decisive battle against the United States has been to gather the main forces of the fleet in the waters around Amami Oshima, and then advance to the sea east of Honshu Island to launch "offshore torpedo warfare" and fleet Armageddon. During the Taisho and early Showa periods, there was basically no major change in this thinking, except for the move of the decisive battle to the Ogasawara Islands. After the London Conference, the Japanese Navy's plan to expand its auxiliary warships was also aborted, and it was further decided to extend the battlefield to the Central and Eastern Pacific, and launch a surprise attack as soon as the U.S. fleet left its home port. The product of the constant revision of this concept is the so-called "nine-stage operation" plan.
The "Nine-Stage Operation" envisages that the U.S. Pacific Fleet and the Atlantic Fleet will roughly split into two groups after the start of the war, and that one group will be the Asian Fleet, with light cruisers as the main force, which should depart from the Philippines. For this fleet, the Japanese side was scheduled to deal with the Third Fleet, which was also dominated by light cruisers. The other group of U.S. fleets, that is, the Pacific Fleet, reinforced by the Atlantic Fleet, is expected to depart from the West Coast of the United States or Hawaii, and will be divided into four groups: a fleet composed of submarines will start a war against Japan, and the other group will be mainly composed of 4 to 6 heavy cruisers, which will be engaged in surprise attacks and harassment missions; The third group, with 14 heavy cruisers as the main force, will serve as the vanguard and reconnaissance mission of the main fleet; The last group consisted mainly of 15 battleships and several aircraft carriers, and was responsible for the main force of the war against Japan.
The Japanese divided the battle against the American fleet into nine stages: the first leg was from the West Coast to Hawaii. After that, the US fleet will occupy part of the Marshall Islands as a bridgehead. The voyage of the U.S. fleet from Hawaii was set as the second leg, and the voyage before the occupation of the Marshall Islands was the third leg. After occupying the Marshall Islands, the U.S. fleet will arrive in the waters of the western Pacific known as the "Inner South Sea," which is the fourth leg of the voyage. The distance from the Marshall Islands to the Japanese near the Caroline Islands was designated as the fifth and sixth sections, respectively. The night before the scheduled decisive battle is the seventh stage, the scheduled day of the decisive battle at dawn is the eighth stage, and the final fleet decisive battle is the ninth stage of the war.
The Japanese Navy's plan was for the fleets to assemble at Truk in the Caroline Islands within 72 hours of the start of the war, using it as a base for advance.
The number of troops required for a nine-dan operation varies with the passage of time. Take, for example, the nine-dan battle plan after the Japanese Navy entered the "no-treaty era" in 1936, which predicted that war against the United States would break out in 1946.
In the first and second sections, two reconnaissance cruisers, three 2,800-ton "flagship submarines," and 27 1,900-ton ocean-going submarines will be used to conduct surveillance along the route. The forces required for the third to sixth sections are four "super battleships" each equipped with 12 508-mm guns, a Zuihe-type aircraft carrier, one reconnaissance cruiser, two "flagship submarines", and 18 large submarines of 1,400 tons. The third and fifth stages will be attacked by large submarines in the form of wolf packs, and the fourth and sixth stages will be attacked by carrier-based aircraft and land-based aircraft, respectively. On the eve of the decisive battle, the Japanese Navy will launch a night attack with a huge torpedo force consisting of 4 submarines, 28 cruisers, and 64 destroyers, and at dawn the next day will launch a supplementary attack with 10 submarines and carrier-based aircraft. In the ninth stage of the decisive battle of the fleet, the final blow will be dealt to the main US fleet with the strength of 10 battleships, 6 aircraft carriers, and 10 submarines.
Judging from the allocation of forces in the nine-stage operation, it has specific requirements for the performance used in each stage. As far as capital ships were concerned, the two naval treaties limited the possibility of new construction, so the Japanese Navy spent 125.8 million yen after 1923 to modernize and overhaul the existing 10 capital ships (for comparison, the Yamato cost 137.8 million yen per ship). Modifications include the addition of underwater mine-protected bulge compartments, the strengthening of armor defenses, the increase in the elevation angle of the main gun to increase the firing range, the replacement of the boiler to increase the power, and so on. The opposition to the treaty in the Japanese Navy has always held the view that "limiting armaments will be more wasteful" and arguing forcefully that it is better to build new warships than to spend a lot of money on repairs to renovate them. However, from a technical point of view, since the new warship project is frozen, the existing warships, which are aging day by day, must be modified according to the progress of naval technology, otherwise they will lose in future naval battles. From an economic point of view, after entering the "Naval Holiday Era," the Japanese Navy's shipbuilding costs have been drastically reduced, and the shipbuilding industry has entered a state of recession.
In terms of aircraft carriers, the Washington and London treaties stipulate that the total tonnage of aircraft carriers for the Japanese Navy is 81,000 tons. In 1930, the Japanese Navy had four aircraft carriers, namely the large aircraft carriers Akagi and Kaga (33,000 tons each), and the small aircraft carriers Hosho (7,470 tons) and Ryusho (7,100 tons), with a total tonnage of 80,570 tons. These four aircraft carriers are organized into two air fleets, which belong to the First and Second Fleets. Large aircraft carriers are equipped with 24 carrier-based fighters and 12 carrier-based attack aircraft, and small aircraft carriers are equipped with 6 ship-based combat and 6 ship-based attack aircraft. At that time, the Japanese Navy claimed that the standard displacement of Akagi and Kaga was 26,900 tons, because according to the provisions of the Washington Treaty, aircraft carriers under 27,000 tons could carry 10 8-inch guns, while aircraft carriers above 27,000 tons could only be equipped with a maximum of 8-inch guns. And these two aircraft carriers are actually equipped with 10 guns. Once Britain and the United States discovered that the tonnage of Akagi and Kaga exceeded 30,000 tons, they each removed two 8-inch guns, which gave them an extra margin of 430 tons.
The 1935 plan was based on the premise that the Washington Treaty would be abrogated at the expiration of the 1936 period, and it was decided to build two new aircraft carriers, namely the Canglong and the Flying Dragon, as well as one replacement ship for the Fengxiang (later the Xianghe aircraft carrier). In addition, the hulls of three more small aircraft carriers were built, namely the submarine carriers Kenzaki, Takasaki, and Big Whale (which later became light aircraft carriers Xiangfeng, Ruifeng, and Longfeng, respectively).
In terms of cruisers, one of the first innovations of the Treaty of London was the appearance of heavy cruisers. Before the London Treaty, countries had different names for treaty-type cruisers, but the United States, Japan and other countries initially continued the name of World War I, calling 10,000-ton cruisers "light cruisers" to correspond to the classification of "armored cruisers". The original design drawings of the Japanese Myo-class cruiser prominently read "10,000 tons, 130,000 horsepower, light cruiser general plan", while the American "Pensacola" and "Northampton" classes were originally numbered CL-24 to CL-31.
Britain divided this kind of "light cruisers" into two categories, one was the 10,000-ton Type A equipped with eight 8-inch guns, and the other was the 8,000-ton Type B equipped with six 8-inch guns, which were called "large cruisers" and "small cruisers" respectively. The Treaty of London divided cruisers into two classes: heavy cruisers armed with 8-inch guns and light cruisers armed with 6-inch guns, and stipulated that the total tonnage of Japan's heavy cruisers was 10840,000 tons. At that time, Japan already had four 7,100-ton Furutaka-type cruisers and four 10,000-ton Myoko-type cruisers, and the remaining tonnage space could also build four 9,900-ton Kaohsiung-type cruisers, for a total of 12 heavy cruisers. Although these cruisers were only 60% of the American in tonnage, they reached 2 3 of the American side in terms of numbers.
Before the two conferences on disarmament, the caliber of the main guns of large cruisers (including armored cruisers) of various countries, the British was 92 inches (234mm), 8 in Germany2 inches (208mm), 7 in France6 inches, 8 inches in Italy and the United States, and 10 inches. The Japanese Navy's purchased ships are 8 inches, and the Furutaka-class and Myo-class, built after the Washington Treaty, are 200 mm (7.).9 inches). After the Treaty of London, the caliber of heavy cruisers in all countries adopted the upper limit of 8 inches stipulated in the treaty, and the Japanese Navy also replaced the main guns of the heavy cruisers, and the replaced 200 mm guns were installed on two coastal defense ships built for the Siam Navy.
In 1918 (the seventh year of Taisho), in the "888 fleet" plan, it was planned to build 3 7100-ton and 6 3500-ton light cruisers, which would be used as torpedo cruisers and reconnaissance cruisers. The 7,100-ton cruiser was later developed into the Furutaka-type cruiser, while the specifications of the 3,500-ton cruiser were later adjusted to 4,100 tons and 5,500 tons.
From 1920 to 1925, the Japanese Navy successively built a total of 14 "5,500-ton medium cruisers" of the Kuma class, Nagara class, and Kawauchi class, which were equipped with seven single-mounted 140mm guns and three triple torpedo tubes, with a speed of 36 knots. In 1922, the designers of the Ship Administration Headquarters, Hiraga Jean and Fujimoto Kikuo, jointly trial-produced the Yubari small cruiser, which achieved combat effectiveness equal to that of a 5,500-ton light cruiser with a tonnage of less than 3,000 tons. As a result of the success of this experiment, Yubari became the mother model of all classes of cruisers in the Japanese Navy.
14 "5,500-ton medium cruisers" (the standard displacement of 5,100 tons is claimed to be external), plus the 2,890-ton Yubari displacement, the total tonnage of the Japanese Navy's light cruisers is 7430,000 tons, 10050,000 tons of the limit is still 2620,000 tons, so the Japanese Navy decided to use these tonnages to build four 8,500-ton cruisers of the highest class (the actual displacement at the time of completion was 11,200 tons, and the displacement of Suzuya and Kumano was 13,400 tons) to replace the Tone-class and Chikuma-class light cruisers built in the Meiji period and retired from 1930 to 1931.
At that time, most of the main guns of the light cruisers of the major naval powers were 6 inches, and the Germans were 59 inches). The Japanese Navy, out of consideration of the Oriental physique, adopted 140mm guns on early light cruisers, whose shells weighed 37 kg, which were lighter than the 45 kg of 6-inch shells, and could be carried by a single person. The London Treaty provided for a light cruiser with a maximum main gun caliber of up to 155mm (61 inch), the Japanese Navy first carried 15 155mm guns on the cruiser of the most advanced rank. After the Treaty of London expired, these main guns were replaced with 8-inch guns, and the original 155mm guns of the most advanced stage became the secondary guns of the Yamato-class battleships and the main guns of the Oyodo-class light cruisers.
In addition, the superlatively first.
The design of ships 5 and 6 was significantly changed, and the Tone-type aviation cruiser was born. In order to arrange the catapults used by large special water reconnaissance aircraft in the rear, the four main turrets of the Ligon type are all concentrated in the bow of the ship, which is very special. In the "nine-stage operation", Mogami and Tone will take on the role of ocean-going reconnaissance cruisers, monitoring the movements of the U.S. fleet during operations from the first to the fifth stage.
As far as the Japanese Navy is concerned, in the era of naval holidays, the technical performance and armament indicators of the capital ship after refit are not much different from the similar ** of other naval powers, and the newly built cruisers have clearly reflected the tendency to strengthen armament. In terms of 10,000-ton treaty-type cruisers, the Japanese Navy's Myoko-type and Takao-type heavy cruisers had two more main guns than most British, French, and Italian heavy cruisers, and one more than the U.S. Navy (except for the Pensacola-class), and the number of main turrets was the largest among the five major naval powers. In addition, the configuration of the Japanese ships reflected the idea of attaching importance to torpedo warfare, and the heavy cruisers were also equipped with more than 10 large-caliber torpedo tubes. However, the destroyers and other small warships used in torpedo warfare were most thoroughly realized in the Japanese Navy.
In the "Kudan Operation", the night torpedo battle on the eve of the decisive battle was of great significance to the Japanese Navy, so the establishment of a strong torpedo force has always been the goal pursued by the Japanese Navy in the Taisho and Showa eras.
To be continued.