In Gammelin's plan, the main forces of the Franco-British army would advance east of the Belgian capital of Brussels, and establish a strong defensive line along Antwerp, Louvain, and Namur. With the Sambul and Maas rivers to lean on, 45 divisions of the Franco-British army dug trenches and built a drum-like trench in just over a month. In front of the Allied forces, the Belgian 22 divisions were holding on to the eastern defensive line that they had operated for many years, with artificial canals and strong fortress groups, enough to make the Germans break a sharp tooth.

The northern theater of operations has been defended as a mountain, and the rest of the theater is equally flawless. The Southern Maginot Line was garrisoned by 2 army groups, and even if the Germans came with 50 main divisions, they would not want to touch Alsace behind the line. As for the central part, Ganmalin is even more at ease. The Ardennes Mountains, considered by the entire European military community to be extremely difficult to march, are comparable to the high and dangerous Alps, and the western foot of the mountains is the raging and wide Maas River, forming a double natural shield for the heart of France. As a precaution, Ganmalin also deployed the 9th Army to the west of the foothills to deal with an enemy that might come at any time.

Although the 9th Army was the weakest of the French forces, with only nine disembodied Division B and a few independent fortified regiments, it felt more than enough to hold back the enemy forces from the Ardennes. First of all, the Ardennes Mountains were not suitable for the passage of large forces, and the 9th Army could have set up a pocket formation at the foot of the mountains to break through the scattered enemies.

Taking a step back, even if the main German army really broke out of the mountains against all odds, then the 9th Army could retreat to the west bank of the Maas River and wait for reinforcements. Dare not say anything else, it is absolutely impossible for the heavy artillery unit to pass through the rugged and precipitous Ardennes forest within five days, so the German troops who arrived on the east bank of the Maas River in the early stage only had infantry, and they did not have the ability to suppress the fire on the opposite bank and force the river crossing. By the time the Germans brought in heavy artillery from the rear, the French had already sent a large number of strategic reserves to support the 9th Army. At that time, in the face of the heavily garrisoned French army group on the west bank, it is undoubtedly impossible for the Germans to break through the natural danger of the Maas River!

Throughout the entire front, from the English Channel in the north to the Swiss border in the south, there is no place that is not strong and solid. Gammelin was confident and prepared to stay behind this front with the Germans for another four years. Now Ganmarin was worried about whether Britain would be able to hold out for so long: since the beginning of the war, the country's navy, which claims to be the world's first, has been defeated again and again, and the strength and weakness of the British and German fleets have long since reversed. If Britain could not support its withdrawal from the war, France, which was alone in its hands, might have the only way out of seeking peace from Germany.

On 3 May, Fang Yan received an order for the first level of combat readiness of the whole army issued by the headquarters of Army Group A. He immediately ended the joint exercise with Rommel's subordinates and pushed his men into a state of imminent battle. During this short ten-day run-in period, Fang Yan asked the pilots to focus on training in identifying enemy targets and familiarizing themselves with the mountainous terrain in France. Both of these are prerequisites that air power must meet in order to support the Army. Due to the short time limit, Fang Yan could only choose to grasp the big and let go of the small, and as for the detailed details of the attack, he could only let the pilots explore it on their own.

Although Fang Yan very much wanted his troops to train for a few more days, time no longer allowed him to prepare step by step. At this time, not only Army Group A, but the entire German Army was ready to attack, and as soon as the attack order from the Supreme Command was issued, it would attack the enemy's territory according to the predetermined plan. Fang Yan knew that the reason why Hitler had not yet set an accurate date for his attack was that in addition to the excuse for invading Belgium and the Netherlands, which needed to be further elaborated, the more important reason was that he was waiting for a suitable weather for a special force.

The most crucial point in the "yellow plan" for attacking Western Europe was to attract the main forces of the Franco-British forces to Belgium as soon as possible. The Ardennes, which had previously been regarded by the German High Command as the most difficult, had now been proven by Guderian in technical detail to be crossable; If the armoured cluster had crossed the Ardennes and the main forces of the coalition had not entered the territory of Belgium in the north, the entire Yellow Plan would have been declared bankrupt.

At that time, the French and British troops would be able to calmly block the German attack in the center and drag the entire front into a stalemate that the Germans were least willing to face. Even if the Germans could still tear a gap in the Allied defense line with the advantage of their armored forces, it was impossible to inflict heavy damage or even encircle and annihilate the main force of the Allied army.

Therefore, the Germans had to launch a thunderous and lightning attack on the Netherlands and Belgium, especially Belgium, which bordered France, at the very beginning of the campaign. Only by beating Belgium to the ground with heavy punches and imminent defeat will the Franco-British forces decide that Germany is still following the same pattern as they had in the last war, that is, choosing the main direction of attack on the northern front, and rush to the rescue. And if the Belgians themselves had blocked the German offensive, it would have been very likely that the Coalition would not have moved eastward: after all, the Germans' main attack on the northern front was only one of the most likely tactics to be adopted, and it was not impossible for the Germans to deploy their main forces in the south with the intention of raiding the Maginot Line!

On the face of it, it seemed that Germany would not have any difficulty in defeating Belgium quickly. Although the latter had a sizable army, its small territory had little strategic depth, and as long as the Germans carried out a pincer offensive with armored units as spears, they could wrap the main force of the Belgian army in two days. However, if you look at the battle map, you will find that the Belgians have built a fortification group on its eastern border that is difficult to penetrate, the most important of which is the fortress of Eben-Emer, which is said to be impregnable and impregnable in the world.

In order to prevent Germany from invading its territory again, Belgium began to make drastic changes to its eastern border in the 20s. The wide Albert Canal was carved out to form a topographic barrier with the mighty Maas River, which flows through Sedan in France and through eastern Belgium; Behind the river was the Belgian army's defensive belt, with all kinds of pillbox fortifications. In order to put a strong "lock" on this defensive gate, the fortress of Eben-Emer was built.

The fortress is located on a granite plateau at the confluence of the Maas River and the Albert Canal. The plateau is 900 meters long and 700 meters wide, with a 40-meter-high vertical cliff facing the river, and a wide anti-tank trench and a 7-meter-high protective wall to the south. The fort has 4.5 kilometers of reinforced tunnels and 1,200 soldiers stationed in it, all of whom can fight in bunkers up to 25 meters below the ground, without fear of their own safety.

Considering that the enemy might saturate the surface of the fortress with a large number of shells and paralyze its combat capability, the Belgians hid and protected all the observation posts and firing points of the fortress. The machine-gun muzzle and field gun emplacements are covered with thick reinforced concrete, and there is no disappearance from the surrounding environment from the surface; The four heavy fortress batteries are even more highly advanced with integral hydraulic drive, which is hidden inside the fortress in peacetime, and quickly maneuvers to the firing port in wartime to launch a fierce artillery bombardment of the incoming enemy. The fort was stocked with plenty of ammunition, food, and water, enough for the defenders to hold out for half a year, and its defensive design indicators learned the lessons of the Liege fortress that year, which could withstand the continuous bombardment of the strongest known French 530mm train cannon.

If the Germans wanted to enter Belgium successfully, they had to break the steel lock of the Eben-Emer fortress. Because the fort's heavy artillery could cover all the crossings on the Albert Canal and the Maas River within a radius of 16 kilometers, the latter's large-caliber artillery group could blow the Germans out of the air if they ignored its presence. Not far northwest of the fortress, three bridges across the Albert Canal connected the Belgian plain, and the Germans had to grab them from under their noses if they were to quickly sweep Belgium.

Even from the perspective of Fang Yan's later generations, the Eben-Emel Fortress, which was built with great investment, was indeed a fortified golden city for Belgium to defend itself against German invasion in the East. Even if the German army kept bombing from the sky with an entire air fleet (army group level) planes, it would be difficult to paralyze the artillery fire of this fortress without ten days and half a month. As for the earth-shattering Gustav train gun, it will not be produced until July next year. If everything goes according to normal flow, Army Group B on the Northern Front will face great difficulties in its feint operations, not only with heavy casualties, but also with a halt in Belgium, leaving the coalition forces without any sense of urgency to support Belgium.

However, the actual process did not follow the normal script. The Belgians made a major mistake, that is, they lacked life experience, they always wanted to make big news, and they did not know the spirit of making a fortune in silence.

After the completion of the Eben-Emer fortress in 1936, the Belgian government invited military experts from around the world to rate the fortress. In order to showcase this masterpiece of engineering and architecture at home and abroad, the Belgians even brought in journalists to provide in-depth coverage of the interior of the fortress. This kind of fanfare undoubtedly gives Germany an opportunity.

Since 1938, attentive German intelligence has collected a great deal of information about the Eben-Emer fortress that the Belgians had unintentionally revealed. One year later, through the tireless efforts of the spy officers, they obtained detailed plans for the interior of the fortress. The German Army then began a careful study of this fortified defensive system. In order to keep the attack plan from becoming mere rhetoric, the Germans replicated the fort in a secret military base in the south for the troops to conduct various simulated attack drills. Soon, they had a complete and in-depth tactical assessment of the fortress.