If anything, it was discovered by the end of the war that defense was stronger than ever. What was just lacking was a comprehensive doctrine on how to properly employ these new tools of war in a defensive posture. To demonstrate the doctrinal gap - the Soviets for instance had only something like 10 pages in their 1941 field manual regarding defensive operations. By 1943, it was half the manual, showing how much the Soviets grew to appreciate and develop their defensive tactics.
The US Army similarly thought of its Armored Division in purely offensive terms - resulting in the initial organization having three tank regiments per Division and nothing else. The Fort Leavenworth exercises then taught the armored forces troops the strength and power of proper defense, which is why they rapidly changed their organization to include mechanized infantry and artillery - both of which are primarily "move offensively, but fight defensively" kind of units.
Really, World War 2 showed that a single battalion on the defensive - utilizing radio to call in artillery and airpower - can now annihilate an entire "elite" Armored Division; like how one battalion of National Guard stopped cold the entire Das Reich at Mortain. It doesn't matter if you have more artillery and airpower to pound that defending battalion - so long as one spotter in the battalion survives with a working radio your attacking Division is going to have a very bad day.
"Stronger than ever" hardly qualifies.
At the similar numbers, German troops could`ve hold the Soviet front almost indefinitely in WW1, but collapsed in a space of less than 2 years in ww2.
You still have to have the air power, and your own artillery is far more in danger, as a great deal of counter-battering fire is available.
Your logistics and reinforcements are extremely compromised, and nobody has to break everywhere, you need a rather small gap, and then something like Bagration can easily happen.
Your example is terrible, as Germans were at huge disadvantage overall in 1944, especially in terms of artillery quality and range.
Yes, the case of one entrenched battalion stopped a division did happened, but look at the other side of things, how Both Germans and Soviets
could often break through the defenses in a meter of hours.
And yes, it does meter with how many guns you pond the enemy, when you`re attacking, where did you get the idiocy that it doesn`t?
Did I also need to mention that Airpower never "annihilated" anything in WW2, it is statistically proven that it`s effect was mostly in forcing enemies maintenance increase, and reducing the combat readiness, while casualties were pretty minor.
In WW1, Allies took almost 3 killed for each German when attacking on Western front. In WW2, the casualty ratio was almost even, both for German offensive in 1940, and Soviet offensives in 1944.
Defenses were important, defense was important, but not nearly as strong
strategically as it was in WW1.
You're forgetting frontage issues.
I`m not. In WW2 attacking division could assume anything from 10-15 km to merely 1.5 km of frontage.
If you want, have a good hard look at what happened at the battle of Kursk. Defences didn`t slow the German army nearly enough, they broke way faster than expected, which forced Soviets to commit their reserves way faster, and caused, for example battle of Prokhorovka where Sovet counter-attack faced way stronger German forces.
Defencive line in the south, that was prepared for month, was broken really fast, and counter-attack fas nececery to stabilise the front.
Now consider that in Battle of Kursk, the defenders, Soviets, had almost 1.3M man to German 900k, they lost noticeable more man then Germans.
Now, the battle of Kursk, was basically more or less similar thing to Battle for Belgium in terms of size, but this time, Germans would have ~20% advantage, due to losing the "divisions of questionable quality", which, by the way, both Germans and France had plenty of.
