The late Menachem Begin was not an officer in the Anders army, but was a rank and file soldier. He also did not see action while serving with this army, which was itself riddled with anti-semitism

The only Polish undergound units that accepted Jews were Communists, who then later, when Poland became a Soviet satelite, showed their true Jew-hating character.

Begin and the majority of Jewish soldiers in Anders army deserted "en masse" when they reached Palestine. Monte Cassino was fought after the desertions.

?? Did you know that the secret police (not only) was full of Jews? They were perfect servant to communist terror (vide Solomon Morel, a butcher, who's wanted by Polish police, but found his shelter in.... Israel).