Based on

Movies like How I Unleashed World War II, Part I: The Escape (1970)

On the night of August 31, 1939, Dolas, from a platoon reinforcing a train station on the German border, falls asleep in a train car and unknowingly crosses into Germany. The moment he shoots a German, who he thinks is a saboteur, the German invasion of Poland begins, and Dolas is convinced it was his fault. He is taken to Stalag POW camp, the first destination in his odyssey around Europe.