In just one day, the landing of 20,000 troops in England was completed with great speed. In fact, these 20,000 people were busy training some time ago to land on a raft. After practicing for so long, this actual combat naturally makes perfect with practice.

After the landing of the army, it quickly surrounded the fortress of Calais and cut off all roads into the interior of France. The British army even sent a large number of soldiers to destroy all the bridges leading to the interior of France, and also dug up many roads to hinder the advance of French reinforcements as much as possible.

Then the army began its assault on the city of Calais. In order to divert the attention of the French defenders from the sewer in the northwest corner, the British army did not attack the northwest corner of Calais when they launched a feint, but placed the feint on the four gates, attracting the enemy's attention to the side of the gate tower.

Then, the British army made a feint while waiting for the rain to fall......

According to the speculation of astronomers at the London court, there could be rain near Calais in the coming days. Once it rains, it's time for the inside and outside to conquer Calais......

On the French side of Paris, François I and his ministers quickly calmed down after an initial panic. Because, good news came from the Calais direction - the British did not immediately take the Calais fortress!

For a very strong fortress like the fortress of Calais, the most dangerous time is actually in the beginning. Because, if you are not prepared for a surprise attack, even the strongest fortress can easily fall.

In addition, the princes of Paris feared that the fortress of Calais had a secret passage left by the British, or that there were British troops lurking in the city to help open the city gates.

Two days later, however, Calais has not fallen. This shows that the British army has no back, and the fortress of Calais is still safe.

If there were no secret passages or internal envoys, the French government and opposition agreed that the British would not be able to storm the fortress of Calais in a few months. So, they began to call up the army with confidence......

Unlike other countries, the French army has become mercenary, and the soldiers are full-time soldiers who are out of work. The French feudal feudal system was more involved. The 15,000 French knights actually don't serve in Paris in normal times. The army stationed in Paris in peacetime was mainly a mercenary army composed mainly of civilians. And those knights who have a fief are actually in their own estates. After receiving the royal summoning order, they will gather in Paris.

When they don't have anything to do, they generally like to stay in a big city like Paris. However, it is spring ploughing time. Most of these knights, who owned their own estates, helped or supervised the cultivation at home, and most of them were not in Paris.

Therefore, if François I wanted to gather reinforcements, it also took time. As for the use of the Paris garrison to reinforce Calais? Impossible, the king's life is not important? Ten fortresses of Calais are not worth the lives of the kings and ministers in Paris......

Moreover, François I and his ministers generally judged that the fortress of Calais would be able to hold on for at least a few months. Therefore, when the knights from all over the country were summoned, they were not asked to come immediately, but left a two-week assembly period.

In the eyes of the French courtiers, the English bandits were by no means the opponents of the powerful French knights on land. Don't look at the English besieging Calais, but as long as the French knight army arrives, they will definitely be able to quickly defeat the English bandits.

It was also true that if the English could not capture the fortress of Calais before the French knights arrived, there was only one way to escape. Because, the army of England is in the field, and it is indeed no match for the French knights. The advantage of longbowmen or something, but it was a few decades ago. Since the introduction of pig iron ingots, the French knights' plate armor English longbows have been difficult to shoot through. After all, the strength of pig iron plate armor is much higher than that of sponge iron plate armor. Moreover, the French army is in Paris, and there are still dozens of artillery pieces that have not been pulled out for use......

That's the general case, though. However, the current situation is not ordinary......

Three days later, the rainy day predicted by the British court astronomers finally arrived......

In the evening, moderate rain fell in Calais. Most of the torches at the head of Paris were extinguished, and only in covered buildings such as the Gatehouse were the torches not extinguished by the heavy rain.

At this time, near the corner of the northwest city wall, several figures came......

They were the spies of the Beihai Kingdom who were responsible for corroding the iron gates of the sewers with aqua regia, and they brought aqua regia that had just been prepared, as well as gas masks to prevent the poisonous gases released during the process of corroding the iron gates with aqua regia.

This is the second generation of gas masks, the first generation of gas masks are made of soft elephant skin, although the effect is good, but not particularly good. The second-generation gas mask is made of vulcanized natural rubber produced in Cuba, and the effect is better.

In the middle of the night, there was no officer on duty on the wall of the barracks that was in charge of supervising the iron gate of the sewer dozens of yards away. After all, they can't even use torches.

But the French were still vigilant, and about every half hour, the barracks would send people to climb the wall in the rain. You can't use torches to keep an eye on it, but you can hear with your ears if there's any movement at the sewer gate. If someone slams the door and picks the lock, there must be a loud noise......

However, they miscalculated......

There were a total of 4 spies sent by the Beihai Kingdom this time, and among them, two were responsible for corroding the large iron locks of the iron gates with glass bottles of aqua regia. The other two, one of whom was responsible for holding a large black cloth umbrella, kept out the rain for the other people, and at the same time, blocked the light......

After all, the two people responsible for corroding the iron lock with aqua regia can't discredit the corroded iron lock......

But they were also not lit with torches or candles, which were easy for the French to spot. They used a very precious lighting device, the Night Pearl......

Although the Night Pearl is very expensive, in order to facilitate the spies' actions, Marin still approved a Night Pearl for this operation.

Before leaving, the four of them illuminated the night pearl in front of candlelight for an hour. Then, the pearl of the night will be able to stay shining for hours.

Although the light was a little weak, not as bright as the candlelight, it was enough to deal with the big iron lock when covered with a black cloth.

Under the black cloth, in front of the iron gate of the sewer in the northwest corner of Calais, two Beihai spies sat on small benches, carefully opened the glass bottle containing aqua regia under the dim light of the night pearl, and slowly poured aqua regia into the iron lock......

It should be pointed out that these four guys, whether they pour aqua regia, hold umbrellas or hold night pearls, all wear second-generation rubber gas masks......

Aqua regia poured on the iron locks and made a corrosive sound of "snort". But the sound was very small, and it was raining at night, so that it could not be heard even on the top of the city......

In the process, a group of French patrols braved the rain to patrol the city walls. They had been in case the English had climbed the wall in the middle of the night, but they had not heard the faint sound of "snorting" from the iron gate of the sewers under the city......

With a faint "snort" as faint as a coke bubbling, the large iron lock of the iron gate of the sewers of Calais was corroded little by little......