Basically, Cavalry together with Highlander Riflemen (Strzelcy Podhalanscy) was the elite in the Polish Army. However, the Elite Infatry - they used horses as means of transport, but fought like a normal infantry, with their own heavy equipment and artillery units.
And if you wonder - YES, there were instances when they broke that rule and did in fact charged at the German (most famous example being Wólka Węglowa, where by charging at entrenching troops they cleared a path for many retreating units), and NO, there were no charges with sabres and lances at German tanks (in fact, lances were no longer in use back then). The whole Cavalry charging at tanks myth was the result of sloppy journalism by... ekhm... Italian correspondent.
GOD DAMN YOU, ITALY!!! AND ALL YOU STUPID MORONS WHO BELIEVE THAT!!!