For the main gun of the "Tone" heavy cruiser, which chose 240mm, which is very non-mainstream among Japanese naval guns, Hu Weidong naturally couldn't help but ask the reason, and this matter actually started from his surprise attack on Fengtai and the total annihilation of the 12th Division of the Japanese Army, which was extremely powerful

After that series of miraculous victories, Japan not only lost tens of thousands of elites, but also lost the equivalent of three field heavy artillery brigades and regiments of heavy equipment, it must be known that there were only five field heavy artillery brigades in Japan at that time, in order to ensure that the army had sufficient fire support, Japan, which had limited heavy artillery production capacity, had to temporarily reduce the production of naval guns in order to free up enough production capacity to accelerate the production of army artillery. Originally, this situation would not last long, but soon after the full-scale outbreak of the war of aggression against China, the Japanese army lost two field heavy artillery brigades in Shanxi, and with the continuous expansion of the war of aggression against China, the Japanese army's demand for artillery is getting bigger and bigger, so the production of naval guns has naturally been repeatedly compressed and postponed

Originally, the Japanese navy and army all had great independence, and the navy could completely sternly reject this kind of practice that seriously harmed the interests of the navy, but at this time, there was a problem within the navy, and the emerging aircraft carrier faction was eager to seize power, and even did not hesitate to cooperate with the army, and in their eyes, the "giant ship artillery" was outdated, and the aircraft carrier and carrier-based aircraft were the focus of the navy's investment, so they did not have much interest in those large-caliber naval guns except for the various anti-aircraft guns necessary to protect the aircraft carrier and the front-line airfield. However, the ships that are still on paper can be adjusted or even changed in design, but the gun barrels of those battleships that have been built still have to be regularly maintained and replaced. And those battleships under construction can't do without main guns, right?

Among them, the former is really not saved, and the cost of replacing guns is huge, and if you do this just to build fewer large-caliber naval guns, it will definitely outweigh the losses. But for the latter, one has shouted that "the new navy will only need two kinds of warships - aircraft carriers and auxiliary ships [in conjunction with aircraft carriers]." But he came up with a good idea, "There is no strong enemy in Japan's coastal waters, as long as there is a strong air force, it is enough to resist the enemy at sea." Mainland, Taiwan, Korea and Manchuria (for those small islands in the Pacific Ocean, fortress artillery is still valuable. (intimidated by the great strength of the Soviet forces in the Far East, the land fortresses did not dare to be removed. Now it's useless. It's long overdue to tear it down to save money. The fortress cannon is too cumbersome for the army to use, so it is just loaded on our warship! Everyone's math. We have more than a thousand large-caliber fortress guns, and even if we remove those that are too old to be used, there are at least a few hundred large-caliber heavy guns that are not outdated, enough to equip dozens of large warships."

As a result, the 203mm L50 main guns of the heavy cruiser "Tone" and its sister ship "Chikumo", which was still under construction, were replaced with eight Type 90 240mm fortress heavy cannons, and because the Type 90 240mm fortress cannon was longer and thicker than the original main gun, if it was built according to the original design plan, the ship's turret was estimated to be unable to rotate at all after installation (Note 1). But how could a high-ranking naval officer bow his head and admit his mistake? He immediately accused the ship itself of being unreasonable, and as a result, the designers were forced to rework the design, and the unique shape of the heavy cruiser's history was stillborn

But in Hu's view, the heavy cruiser Tone, which was designed to return to tradition, was undoubtedly more powerful than historical prototypes. Eight main guns can be used to the full potential, compared with reducing the losses of three water reconnaissance aircraft, it is definitely more than a loss, and the Type 90 240mm heavy cannon, although it is not a very advanced product, but the performance is really good. Far better than the original main gun. First of all, the caliber is there, for the main gun, the caliber means the power, and the 203mm main gun can't be compared with the 240mm one, and the Type 90 240mm heavy cannon inherits the advantages of high accuracy and long life (at the cost of slow rate of fire) of the Japanese artillery. It also has an unbelievably terrifying range, even when firing ordinary 240mm shells (non-special shapes, no additional charges, no boosters). It can also easily hit 50 kilometers away, and although the original 203mm naval gun also has a good range of close to 30 kilometers, it pales in comparison with it. Naval guns, especially the main guns, are typical "one inch long and one inch strong", the range far means that the enemy can shoot first in the artillery battle, if the speed has an advantage, it can also make the enemy only beaten but unable to fight back, more importantly, the firing range of the cannon is generally high projectile muzzle velocity, and this means that the shell penetration is strong, and this is more important than anything else in the era of giant ship cannons...,

One may ask, since this fortress gun is so good, why did the Japanese Navy not use it as a naval gun before? It turned out that, on the one hand, because the ships of the Japanese Navy did not have a tradition of being equipped with this caliber of artillery before, if this new caliber was suddenly introduced, there would be a lot of pressure on logistics; The bigger problem is that this caliber is not high or low, and the same 203mm naval guns cannot penetrate the main armor of the battleship, and it is a bit wasteful to deal with the cruiser, the army was still interested in it, but its terrifying weight of more than 50 tons finally discouraged the army, and the almost impossible to maneuver artillery is of no practical value to the army, even if it is powerful. Fortunately, the firing range is very important for the fortress gun that does not need to be maneuvered, and the gun is exempt from layoffs, but due to the high cost, the number of production is not very large, if it is not due to the early appearance (put into active service in 1930), the number of stocks is simply not enough to equip a few large warships

Note 1: Historically, the gun emplacements of the Tone-class heavy cruisers were very strange, with all 8 main guns arranged at the front of the hull, and the rear of the hull arranged as a special seaplane operation area. The appearance was quite special at the time. The advantage of this configuration method is that it can increase the carrying capacity of the seaplane and make the take-off operation of the aircraft more convenient. In addition, the muzzle flame and storm caused by the main gun firing can also be avoided on the aircraft. The disadvantage of this configuration of the Ligon class is that the turret occupies a large space on the hull deck, and there are dead spots in the main gun firing boundary.

Personally, I think this design is quite advanced, but unfortunately the turret is not a missile launcher, a seaplane is not a carrier-based helicopter, in the way of naval warfare at that time, this design is definitely not worth the loss, for the cruiser with artillery as the main means of attack, no matter how important the seaplane is, how can it be compared with the main gun? (Your support is my biggest motivation.) )