Watch Katyn full movie online Movies123. Watch Katyn 123movies online for free. Katyn 123Movies: On September 1st, 1939, Nazi Germany invades Poland, unleashing World War II. On September 17th, the Soviet Red Army crosses the border. The Polish army, unable to fight on two fronts, is defeated. Thousands of Polish men, both military and government officials, are captured by the invaders. Their fate will only be known several years later.