Kagemusha Tokugawa Ieyasu

Keicho era, with the Toyotomi and Tokugawa armies poised to clash at the edges of Sekigahara .... Jirosaburo, a wandering warrior, is by Tokugawa Ieyasu's side at the head of the army as his shadow. The two men are so similar that few can tell them apart -- save for the sharp eye of an assassin, lurking among the troops. When the real Tokugawa Ieyasu falls to the assassin's blade, Jirosaburo throws away his identity and assumes Ieyasu's destiny of conquest and unification.