Why did the impregnable fortifications after World War II finally become a joke?

Mainly the development of science and technology.

With the development of science and technology, mankind has made great achievements in many aspects, such as the destructive power of weapons, the effectiveness of investigation and strategic planning.

1, artillery

With the development of science and technology, the caliber of artillery is getting bigger and bigger, the power of artillery shells is getting bigger and bigger, and the projection distance is getting farther and farther.

During World War I, the Belgian fortress Liege blocked the German attack. At that time, I hoped that the fortress could resist for three to five months to buy time for the arrival of reinforcements. General Le Mans confidently thought: "Liege is an indestructible fortress. Even if the Kaiser himself comes, he will be defeated!" The Germans immediately mobilized the Dabosha "420mm siege howitzer (which can fire nearly 1 ton shells to14.5km away). On August 65, 438+02, "The Great Bertas" arrived at the front line to participate in the war. Within 24 hours, Ponty's battery was shot 45 times, almost completely destroyed. On June 16, the resistance of Fort Liege ended.

During World War II, the Soviet fortress Sevastopol blocked the German attack, and the Germans immediately took out an 800mm Dora gun (which can fire nearly 7. 1 ton of armor-piercing bullets or 4.8 tons of high-explosive bullets 28-47 kilometers away) and set up an ammunition depot 30 meters underground.

2. Air Force

With the development of science and technology, planes fly higher and higher, and the bomb load is increasing.

The three-dimensional war makes the weakness of the fortress very easy to be attacked by the other side.

3. Means of investigation

With the development of science and technology, more and more people,

It is easier for local authorities to grasp weaknesses.

4. Transport capacity

During World War I, because of the lack of transportation capacity, after the German army opened the breakthrough, the follow-up troops could not follow up to stabilize the breakthrough or expand the results (Battle of Marne River). Instead, the French army fighting on interior lines mobilized its troops to stabilize its position and fight back (at the Battle of Marne River, the French army collected more than 600 taxis overnight and sent a division to the front, which became the key to the victory of the British and French allied forces. )