Kagemusha (1980)

Lord Shingen's decoy is discovered to be a fake when the concubines notice he doesn't have a battle scar that the real Shingen has (the concubines inspect the decoy's body after he falls off a horse). Now that the deception has been discovered, there's no choice but to stop using the decoy. Shingen's decoy is thanked for his work and ordered to leave. Shingen's two enemies, Nobunaga Oda and Ieyasu Tokugawa, are informed that Shingen's funeral is being held and Nobunaga sees that Shingen successfully deceived him with a decoy for three years. With the decoy no longer in charge, Shingen's son (Katsuyori) is heir to the seat of power and he decides to attack Nobunaga and Tokugawa. As Katsuyori and his troops march on, they notice a rainbow and the generals warn Katsuyori that it is a sign from the late Shingen telling his son to not attack. Shingen's decoy follows the troops and they are defeated in battle by Nobunaga and Tokugawa's troops. Shingen's double walks among the dead soldiers, gets a spear and charges at the enemy troops. He is shot and walks to the nearby water where he falls dead.

A.J.