Shotgun
A young, drunk, civil war hero travels to Japan with his shotgun to take on the yellow savages armed only with swords. After being captured, he ingratiates himself into their culture and in a matter of months is able to out-sword the swordsmen even though they've been training practically since birth. In the end the poor yellow savages all die and the white savior is left to carry on their ways.
Wait!! Didn't they already make that movie?