By the middle of the Warring States period or around 1550, several Buddhist sects including the Ikko sect headquartered near present-day Osaka and the Tendai monks on Mt. Hiei near Kyoto had acquired large military forces which they used to protect themselves and to influence the tumultuous politics and wars of the period. These sects came into conflict with secular leaders seeking to unify Japan, especially Oda Nobunaga and Toyotomi Hideyoshi. Nobunaga in particular took exception to the power held by the sects since he found himself frequently opposed by them. In 1571, Nobunaga attacked the monks on Mt. Hiei and destroyed the Enryakuji monastery. Later, in 1580, he also destroyed the Ikko sect in most of its strongholds. For practical purposes, the military power of the Buddhists quickly waned after 1580.
