What Did You do in the War, Daddy? (1966)

In this service comedy set during World War II, Capt. Cash (Dick Shawn) and Lt. Christian (James Coburn) are given orders to invade a small but strategically important village in Sicily. To their surprise, none of the natives offer the slightest resistance to the Americans taking over their town, who present only one stipulation -- the main event on the town's annual social calendar, a football match followed by a wine festival, is scheduled to happen in a few days. If the Americans would be kind enough to let them have their party, they'll hand over the town without a fight. Cash and Christian think that this plan sounds reasonable enough, and a few days later they and their men are drunkenly whooping it up with the townspeople when both German and U.S. surveillance planes spot the festivities. Thinking the wild party looks more like some sort of battle, both the Germans and Americans make plans to send in troops. Screenwriter William Peter Blatty would enjoy greater success a few years down the line with The Exorcist, a novel about a different sort of conflict.