I haven't claimed that there were zero such instances, but my guess is that such battles in difficult terrain may be ~ 5 per cent of the total, if not less. People and animals get exhausted easily in bad terrain, and it is hard to supply the troops. Even mechanical equipment becomes less reliable and more prone to malfunction.
Notably, the German operation Sichelschnitt in 1940 was very successful because the French command considered it unlikely that German Panzers would be able to cross the Ardennes in force, even though the French command was probably well aware of their own military history.
Notably, the German operation Sichelschnitt in 1940 was very successful because the French command considered it unlikely that German Panzers would be able to cross the Ardennes in force, even though the French command was probably well aware of their own military history.