Jupiter's Darling (1955)

The Love Story of the Beauty and the Barbarian! Clash of Armies! Underwater spectacle! Never before such sights to see!

Rome is on the verge of being conquered by Hannibal. While Rome's ruler, Fabius Maximus, plots a defense against Hannibal's armies, Fabius' fiancée, Amytis, is curious about the fearless conqueror. Amytis travels to Hannibal's camp just to get a look at him, but she ends up being captured. However, she is instantly smitten by the Carthaginian commander, so she tries to shift his attentions away from Rome -- and to her instead.