Although several Japanese bomber pilots accurately dropped the ground-penetrating bombs on the top of the three main batteries of the U.S. fortress on Oahu from a height of 3,000 meters, they could not penetrate its incomparably strong top protection. The reason is very simple, these coastal fortresses are basically built on the mountain, so the top is basically at least a few tens of meters thick mountain soil and stone layer, and according to a certain master of the arts, the pilot who flew close to see what was going on, the US military also artificially built a baffle structure about three or four meters thick on the top of the fort, as for the material, Yamaguchi knew that it should be reinforced concrete when he thought about it

"They can't help themselves with such a high standard of fortifications, right? It's not such a waste of money (Note 1)! Yamaguchi was so aggrieved that he almost roared out in anger, and his heart couldn't help but be discouraged, if he couldn't conquer the coastal fortress with the strongest firepower on Oahu, the Japanese marines would not be able to land, and under the premise that the enemy could not land, even if the American army's will to fight was low, it would never surrender to him, and if the American army did not surrender, all his previous plans would be just a flash in the pan

"I can't imagine that after calculating for so long, the Mi army only needs to build the fortress strong enough to completely crack it, and that's probably the case with 'one force to reduce ten wisdom', right?" , Yamaguchi thought a little disheartened. However, Yamaguchi's tenacious temperament has always been tenacious, and it didn't take a few minutes to regain his strength, although he had said before that "if you can't win, you'd rather lose quickly", but after all, he still didn't want to admit defeat. Since Oahu cannot be occupied, it is necessary to destroy as much of the military supplies stored here as possible.

Japanese spies have not yet found the location of the main ammunition depot of the US army, and Yamaguchi has speculated that it may be hidden deep inside the mountain (in fact, more than 300 meters from the surface of the mountain), so he has nothing to do about it, but as long as the weakly defended US oil depot is burned, it can also greatly delay the US counteroffensive, after all, 4.5 million tons (Note 2) of refined oil is not a small amount, even if it is as strong as the United States. Nor can it be re-procured in a short period of time and shipped to Hawaii anytime soon

While Yamaguchi was thinking about how to burn off the fuel in the US military stockpile, and at the same time thinking heartily about which ships to abandon in order to concentrate the remaining fuel of the fleet to ensure the return of the capital ships, the commander of the First Air Fleet, Jizaburo Ozawa, had been patiently asking about the situation from the pilots who had returned from a failed mission, especially the guy who had bullied the US army for running out of large-caliber anti-aircraft guns and flew close to several US batteries to take a look. When Yamaguchi Tashi gritted his teeth unwillingly and prepared to give the order. Jizaburo Ozawa suddenly came to him and said in a low voice, "Your Excellency Commander, there is still hope. ”

Jizaburo Ozawa, six years older than Tabun Yamaguchi, was the first Japanese admiral to realize that aircraft carriers would replace battleships. But it has not been reused historically. This time and space is highly recommended because of Yamaguchi's many smells. And for the first time, the opportunity to command an aircraft carrier formation was obtained. Although Yamaguchi Tabun thinks highly of himself, he has always respected Jizaburo Ozawa very much, and now he suddenly said such a thing. Yamaguchi's eyes suddenly froze, and he waved his hand lightly to signal the senior to speak in detail.

So, Jizaburo Ozawa shared some of the information he had just learned with his own ideas. It turned out that some pilots noticed in the course of carrying out the mission that the main battery on the coast of Oahu can be roughly divided into two categories, one is that the barrel of the giant cannon can be fully extended, and the angle at which the turret can rotate is therefore very large, and the minimum will not be less than 180 ゚, and even 270 ゚ is not absolutely impossible, so even if it is facing the landing site at a large angle, the giant cannon of this kind of battery can be completely hit, so it poses a great threat to the enemy's landing force.

But because of this, the emplacements had to extend the reinforced concrete baffle outwards to protect the rotating turret, as if a semicircular lid had been added to it, and in Ozawa's view, this "cover" structure, which was supposed to serve as a protection, was a weakness that could be exploited

"Without the protection of the mountain soil and rock layer, it is indeed relatively weak, but the reinforced concrete with a thickness of three or four meters is still a strong protection, even if it is a ground-penetrating bomb, it may not be destroyed! Moreover, the area of that cover is much smaller than the entire top of the battery, and the plane must reduce the altitude to ensure the hit rate when dropping the bomb, so that the kinetic energy of the ground-penetrating bomb is insufficient, and the penetration will also be affected, and it will be more difficult to destroy it", Yamaguchi Tawen's face was slightly happy, but he was still not as optimistic as Ozawa Jizaburo.

"It looks like it's three or four meters thick, but it's very different from the top guard of the battery itself. The top shield of the turret itself is connected in all three directions, and when it is subjected to the force of impact, it can be fully distributed; And this kind of semi-circular lid structure that extends out is different, it is only connected to the main body on one side, and the impact force it can withstand will be relatively small, and even its own weight alone is already a big burden", Ozawa Jizaburo said with an analogy, "The larger the outer drift of the air carrier, the more planes can be carried and dispatched at one time, but it can only be added to 5 meters, in fact, the same is true!" ”

Note 1: Before World War II, the U.S. military spent no less than $1.5 billion on Fort Oahu (enough to build 14 Iowa-class battleships at 1940 prices.) Considering that the construction of the project had been under construction since 1910, the magnitude of inflation during that time was not small, and the actual cost was much more than that

Note 2: It is also said that it is 4.5 million barrels (about 700,000 tons), but considering that a capital ship consumes tens of thousands of tons every month, as the main material storage site of the US Pacific Fleet, only 700,000 tons of oil is too little, which is not in line with the US military's traditional style of deep pockets and waste of energy, and also contradicts Eisenhower's view that if the Oahu oil depot is bombed, it will delay the US counteroffensive for two or three years (700,000 tons can be directly called from the mainland's strategic reserves, And in terms of capacity, there is no need to worry, the Americans will be able to refill Oahu's oil depot in a month. Therefore, I personally think that 4.5 million tons is more realistic, and this statement is used in the book (to be continued......