The Last Legion
(2007)

They win the battle against Vortgyn and the Goths. The last Caesar, Romulus Augustus, declares an end to fighting and they settle down in Britania. Aurelius (Colin Firth) survives his wounds and marries Mira (Aishwarya Rai).

Romulus eventually marries Ygraine and becomes the father of the child who will eventually become King Arthur. Ambrosinus (Ben Kingsley) survives them all and becomes Merlin.

Thanks Mary C!