The New Adventures of the Elusive Avengers (1968)

In 1920, as Crimea nears liberation from the White Guards, four resourceful Red Army soldiers on patrol unexpectedly shoot down an enemy plane. Inside, they find a secret report revealing strong defenses around a Red-held coastal city. Tasked with obtaining a map of these fortifications, the young soldiers must undertake a crucial mission to help their comrades secure the city's liberation.