The Onin War tore Japan apart, but also kicked off the Sengoku Jidai or Warring States Period that's a seminal part of Japanese history. The power of the shogun dissolved and regional clan leaders or daimyo fought for control of the country. In the mid 16th century, near Kyoto, a clan called the Matsudaira found itself pinched between two great rivals: the Oda and the Imagawa. Abducted as a hostage by the Oda, the scion of the Matsudaira clan (the young Tokugawa Ieyasu) grew up to fight alongside of the Imagawa when he was released. Their combined forces threatened to destroy the entire Oda clan, but Oda Nobunaga had a different idea. They clashed at the Battle of Okehazama.