At the mouth of the Liao River, there was originally a small castle called Niuzhuang. This fort was originally built at the mouth of the Liao River by our Qing Dynasty to prevent the Ming Dynasty sailors from attacking along the Liao River. But in the repeated tug-of-war with Zheng Zhihu's "Dengzhou Water Division", it was burned. Later, after the Manchu Qing Dynasty moved the coastal villages, the castle was not rebuilt. However, after the model army attacked Jinzhou along the Liao River, the Manchus sensed the importance of the castle again, so they rebuilt the castle again, and greatly expanded its scale.

The original Niuzhuang Fort was actually just a wooden walled city, which was slightly larger than a beacon tower, and the army that could be stationed was only about 50 horsemen. But now, Ken Yan has seriously expanded it. Today, the castle has a wall more than seven meters high, with a brick wall on the outside, the circumference of the city wall is almost 2,000 steps, at least more than 1,000 troops are stationed in the castle, and some heavy artillery pieces cast by the Manchus themselves to block the river and sea are also erected on the city.

Lord Nelson, the later Admiral of the British Navy, once said: "A gun emplacement with one gun is enough against a ship with a hundred guns." Of course, this is true, because the battery has an incomparable advantage over the battleship, that is, no matter what, the battery will not sink. In an artillery battle between the two sides, the battleship must accurately hit the cannon on the turret in order to achieve effective killing, but the turret only needs to hit the opponent's warship. Moreover, because the turret is backed by a solid earth, it can completely ignore the increase in weight and defense, as long as the design is reasonable, the turret's resistance to attack can easily exceed the upper limit of the attack power of the ship's guns.

However, all this requires a number of prerequisites, first of all, the battery must be properly designed. Secondly, the artillery used in the battery should not have much difference in performance with the naval gun.

I can't do either of these things. The walls of Niuzhuang Fort are almost vertical, which is very beneficial against enemy infantry, but in the face of artillery fire, such walls can easily collapse in large areas, so this is not a good design. In addition, in terms of artillery technology, the difference between our Qing Dynasty and the model army is still very big. Therefore, although the heavy guns they cast were many times heavier than the naval guns of the model army, the range and power were not as good as the naval guns of the same level of the model army.

However, even so, the Niuzhuang Fort is still a great threat to any attempt to use the Liao River to harass the Jiang. Therefore, how to take out this fortress has become a matter that the model army has been studying.

According to reconnaissance, the fortress was equipped with more than 40 guns, but most of them were actually smaller Furlong cannons, and only 11 larger guns. Seven of them were cast by the Manchus themselves. Although these cannons weighed more than 6,000 catties, the weight and range of the shells fired were actually only comparable to the 12-pounder guns of the Model Army. The other four cannons were 24-pounder cannons captured from the Ming army, and these cannons were still produced by the Zheng family's artillery factory. These foreign trade versions of the guns did not use technology including multi-layer barrels, and their performance was far inferior to the models used by the Zheng family. However, because of the use of forged drilled barrels, (since this technology matured, the Zheng family almost gave up the technical research of directly pouring barrels, so even the monkey version of the cannon in foreign trade uses such a barrel) This cannon is still quite advanced in technology compared to other artillery. Both in range and power, they significantly surpassed those 12-pounder guns in the North Sea Nursing Home (the nickname of the Northern Fleet of the Model Army Navy). Therefore, according to Shi Lang's calculations, if the fleet goes up to shoot, considering the limitation of the shipping lane, the number of warships that can be put into operation at one time is very limited, and I am afraid that even if it pays a great price, it may not be able to suppress the firepower of the Niuzhuang fortress. And if the artillery of Niuzhuang cannot be suppressed, it will take longer for the landing marines to capture Niuzhuang at a greater cost. Considering again, once Niuzhuang goes all the way to Jinzhou, there are beacon towers. Once Niuzhuang is attacked, the Qing army in these places will soon be able to come to the rescue. Therefore, the Northern Fleet has never found any good way to deal with the fortress of Niuzhuang.

Another month, as a result of the commissioning of the new warship, the Model Navy transferred to the Northern Fleet a battleship captured in a naval battle with the Spaniards, now named "Fuyuan". The battleship had two decks, more than thirty cannons on each side, and most of the guns were replaced with self-produced 18-pounder guns, and in terms of firepower alone, the ship was enough to suppress the fire of the Niuzhuang fortress in a short time and support the Marines to take the fort.

However, another problem is in front of everyone, that is, the draft of the "Fuyuan" is too deep. Niuzhuang fortress is at the mouth of the Liao River, the sediment carried by the river gradually silted up at the mouth of the river, making the depth of this sea area generally relatively shallow, even if it is a warship such as a cruiser, it must be very careful to act in this area, otherwise it may run aground, and a big guy like a battleship can only enter this sea surface carefully at high tide. Such restrictions made it very difficult to throw in battleships to destroy the fortress.

However, during a routine hydrographic survey, Shi Lang's fleet found that there were some deep ditches under the sea near the Niuzhuang Fortress. Even at low tide, these deep ditches are more than three zhang deep, and one of them can directly allow the Fuyuan to approach only a hundred meters away from the Niuzhuang Fort. The existence of this trench was not only conducive to the attack on the fortress of Niuzhuang, but also made him think about some other things. These days, Shi Lang has been busy with hydrological exploration in this area, and now, this work has been basically completed.

According to Shi Lang's original idea, sending a battalion of marines, plus a battleship and two cruisers for fire support, should be able to destroy the Niuzhuang fortress again before the enemy support force arrives. However, the news that Jianxuan might enter the customs again gave him a new idea. That is, the fleet and the marines should not only take the Niuzhuang fortress, but also take advantage of the absence of the enemy's main force, relying on this trench, at the entrance of the Liao River, with the help of the existing Niuzhuang fortress, to transform it into a brand-new fortress with a port. If such a plan was realized, the Manchus would have to make a difficult choice: to attack a fortress with a port that could not be surrounded with a small number of warriors of the Eight Banners; Or do you just let it go there and watch the Model Army continue to encroach on this castle to the north? Shi Lang felt that no matter which choice it was, it was not a good thing for Jianxin.