Fourth Shinobi World War

The beginning of the Fourth Great Shinobi World War is declared by Madara Uchiha when the five Kage refuse to give him the Eight-Tailed Giant Ox and the Nine-Tailed Demon Fox. He has stated that he will use the seven tailed beasts already captured by Akatsuki in combating the ninja world.

Years earlier, Itachi Uchiha had prevented the outbreak of a Fourth Ninja War by carrying out the Uchiha Clan Massacre.