On the Western front, and tgat was as much the machine gun, and artillery, as it was field fortifications. WW1 on the Eastern front was very much mobile warfare, including cavalery. Until WW2, for what it's worth.
EDIT: People tend to see the Wehrmacht as this fully mechanized beast of an army. Truth is the vast majority of soldiers walked into battle, with animal drawn carriage for their stuff from food to field guns.
Quite fascinating topic, horses in WW2. I'll have to some more research on this.
There’s a new book on cavalry in WW2 being published soon look out for it.