The Polish cavalry were very good - but reports of their steadfastness and elite status stem from actions like Mokra where they were entrenched (difficult to entrench mounted cavalry
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)in a defensive position. The charging against tanks is one of those propaganda myths I'm afraid. I'd let them charge but they should get shot to pieces - they did charge successfully at least once, but against surprised infantry not tanks, and then were shot to pieces by supporting armoured cars following the infantry (I know-wrong way round somehow but there you go- maybe the Germans threw a double 6
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).