. I know the Polish army did use cavalry but apart from grudging admiration for their courage the reports I read spoke of total and utter disaster for the mounted troops.
The Polish "disaster" was an artifact of National Socialist propaganda. Never actually happened (ie: charging tanks on horseback).
At least two "grand charges" in WW2 destroyed mounted units. In 1942, an Italian cavalry regiment rode down and destroyed a Russian rifle regiment, using sabers and grenades. In 1944, a Hungarian cavalry regiment did the same thing to a Romanian force.
Granted, most of the major contributions to the war were in terms of recon and anti-infantry work, but cavalry still did (and still does) play a role, when properly utilized.
Not suggesting anybody take up a lance and charge a machine gun nest, but still, the precedent is there.
-Doc