The Polish Army was rather backwards by WW2...

They still had the best cavalry in the world, but by this point in time cavalry generally didn't make much of a difference on who won a war. The simple fact that Poland had a backwards army made them have no chance against the Russians or Germans.

But I do believe that they held out longer than the French, heck even the Belgians almost held out as long as the French. Yea sure, so what if the Wehrmacht was the most-advanced best-equipped most-efficient army since the Mongols and Romans, but they could have at least held out a few more days.......

French resistance afterwards helped a lot though, they did more for the cause than the army