Generate a question about the following movie plot: "The Captain" (Michael Caine) leads a band of mercenaries who fight for the highest bidder regardless of religion. His soldiers pillage the countryside, and rape and loot when not fighting. Vogel (Omar Sharif) is a former teacher trying to survive the slaughter of civilians occurring throughout south-central Germany. Vogel runs from the Captain's forces, but eventually stumbles upon an idyllic mountain vale, untouched by war and still living in the age before the war. The Captain and his small band are not far behind. Trapped in the valley, Vogel convinces the Captain to preserve it and the village it shelters for their own benefit, as the outside world faces famine and devastation. "Live", Vogel tells the Captain, "while the army dies." The Captain decides that his men will indeed rest here for the winter. He forces the locals to submit, especially their Headman, Gruber (Nigel Davenport). The local Catholic priest (Per Oscarsson) is livid that the mercenaries include a number of Protestants (and nihilistic atheists for that matter), but there is little he can do to sway the Captain. The mercenaries are of one mind after the Captain kills a dissenting member of his band, and religious and ethnic divisions are set aside. At first, the locals accept their fate. Vogel is appointed judge by Gruber, to settle disputes between villagers and soldiers. As long as food, shelter, and a small number of women are provided, the mercenaries leave the locals alone. Hansen (Michael Gothard) attempts to rape a girl and, exiled from the group, manages to lead a rival mercenary band to the valley, before the winter sets in and closes the valley to all outsiders. He and his band are destroyed and the valley goes into hibernation. But as winter fades, it becomes obvious that the soldiers will have to leave. The Captain learns of a major military campaign in the Upper Rhineland and decides to leave the valley in order to participate. Vogel wants to accompany him, fearing Gruber will have him killed once The Captain leaves....
Where is the military campaign that causes the soldiers to leave the village?