Reread your history books bro… They held Warsaw and Hitler had to divert troops from the west to help defeat them. Unfortunately, unknown to most and not in the history books. The Polish thought the Russians were their friends and went east to meet them. The Russians killed all the Poles that they saw coming.
Finally Warsaw surrendered with the agreement that the POWS would be treated as POWS. Hitler executed all the males.
Poland fared the best against the Germans. The source of all the Polish jokes are actually from the Germans. It was the rainy season and they figured that tanks would get caught in the mud. So the solution was to have the Polish cavalry ride through the mud and destroy the German tanks. Unfortunately the rain never came and the Germans in fully mobile tanks were laughing at the Polish attacking them on horseback.
Remember that up until WW2 there was no real mechanized war and horseback was still the majority of how fighting was done.