Theoretically, Erwin's judgment was correct.
Namur Fortress is not like the chalky hard ground of the River Somme; here, there are rivers, forests, and soft terrain everywhere.
When the rainy season comes, the "pitter-patter" of the rainwater soaks the ground, making it soft and sticky. Even without tanks, simply walking on it would bring mud onto one's shoes, making it difficult to walk.
This is extremely disadvantageous for the attacking side, especially with barbed wire and anti-tank ditched ahead. A rash attack could result in a disaster similar to the Battle of the Somme, where tens of thousands of men were wiped out in a day, turning victory into a crushing defeat in an instant.
This is also one of the reasons why it is commonly believed that Namur Fortress is unsuitable for an attack by Shire's armored forces.
However, since Shire decided to target Namur Fortress, he naturally had a way to deal with it.
...
