With his frontiers relatively secure, Oda Nobunaga prepared for a threat much closer to home: the Ikko-ikki. These religious communities comprised new-style warrior monks of the Shinshu sect. Turnbull explains, “The second term in the name, ikki, strictly means league. … The other word, Ikko, provides a clue to their religious affiliation. It means ‘single-minded’ or ‘devoted,’ and the monto (disciples or adherents of the Shinshu sect) were completely single-minded in their devotion and determination.” The Ikko-ikki grew out of the Onin War and out of the tradition of earlier warrior-monk sects. Whereas earlier sects had some trained fighters, they depended mainly on mercenaries; the Ikko-ikki recruited from the peasantry and depended on fanaticism. The Shinshu sect grew out of a breakaway movement from Pure Land Buddhism and was organized in the first half of the fourteenth century by Kakunyo, grandson of the Pure Land sect’s founder, Shinran. He established the movement’s headquarters at the temple holding his grandfather’s ashes, Honganji.
The Shinshu sect turned away from traditional monasticism taught by other forms of Buddhism in order to preach that enlightenment came merely from uttering the name of Amida Buddha, for it grew from an inner urge placed there by Amida. This simpler form of enlightenment was attractive to the peasantry, who had neither the time nor spiritual drive to become monks. The Ikko-ikki communities were started by Rennyo, the eighth leader of the Honganji, at the end of the fifteenth century. Turnbull writes, “Their faith promising that paradise was the immediate reward for death in battle, the Ikko-ikki monto (believers) welcomed fighting; nothing daunted them. When the Ikko-ikki were about to go into battle, the sound of their massed nembutsu chanting chilled the blood of their enemies.” By Oda Nobunaga’s time the Ikko-ikki were established in an area virtually equivalent in size to his own, and they were an opposing economic force as well as a military one. Further, when relations between Nobunaga and the shogun went sour, Yoshiaki began courting the Ikko-ikki as well as some of the daimyo. Clearly, the warrior monks and the new militant church, the Honganji, would have to be dealt with if Nobunaga was going to establish his dominion.
The Ikko-ikki were based in temples throughout the region from Kyoto westward, but their three primary centers were at Enryakuji just to the north of Kyoto, Ishiyama Hongonji further to the south (the site of Osaka Castle today), and Nagashima some fifty miles east in the province of Ise, next to its border with Oda’s Owari Province. All were built in easily defensible areas, Ishiyama Hongonji and Nagashima in marshy river deltas and Enryakuji atop Mt. Hiei overlooking the southwestern shore of Lake Biwa.
The Ikko-ikki traditionally fought with a halberd-type spear, the naginata, which sported a long, wide, curved blade. By the Sengoku period, however, they had not only adopted firearms but were engaged in manufacturing them as well, using the organized and cohesive nature of the Shinshu communities. That same cohesiveness, coupled with discipline and motivation, allowed them to develop into masters of both offense and defense.
Oda Nobunaga began his struggles with the warrior monks in 1570. After his victory at Anegawa in midsummer, he launched an offensive into Shettsu Province, south of Kyoto, against the daimyo Miyoshi Yoshitsugu, leader of one of the clans threatening Kyoto. Miyoshi was able to draw on 3,000 arquebusiers from the nearby Ikko-ikki temple at Ishiyama Honganji, a reinforcement that obliged the Oda forces to withdraw. Turnbull asserts that “Nobunaga’s army was stunned both by the ferocity of the surprise attack against it and also by the use of controlled volley firing from 3,000 arquebusiers.” This is the first mention of volley musket fire in history.
When Nobunaga marched to Mt. Hiei against a reconstituted army under Asai and Asakura in the winter of 1570–71, Ikko-ikki forces surrounded and forced the surrender of Ogie Castle, commanded by one of Nobunaga’s younger brothers, who committed suicide in shame. That loss, coupled with the blame he placed on Buddhist priests for his father’s death, must have renewed Nobunaga’s personal hatred and coupled it with his political and military needs. Additionally, monks had again aided his enemies during the battle against Asai and Asakura, when 3,000 gunmen from the temple at Enryakuji struck the Oda flank.
Starting on 29 September 1571, Nobunaga moved to eradicate the league in a most brutal way. Starting with the town of Sakamoto at the foot of Mt. Hiei, Nobunaga’s army of 30,000 moved toward Enryakuji at the summit in a scorched earth advance, destroying everything in its path. The Ikko-ikki could do little against Nobunaga’s large and highly trained samurai army, which destroyed the temple at Enryakuji. All the sources describe it as more slaughter than battle, with every structure burned and every person—man, woman, or child—killed in battle or taken captive and beheaded. Nobunaga’s reputation for cruelty grew primarily from this occasion, but the action was effective. Although the temple was later rebuilt, the army of monks based there was never revived.
Nobunaga next moved to focus on Nagashima. An earlier assault in May 1571 had been led by two of Nobunaga’s subordinates. They tried to send their cavalry through the marshes but were bogged down in the mire, at which point they were slaughtered by Ikko-ikki gunners and archers. Most of the attacking force was killed. Nobunaga led the next assault in the summer of 1573, using his own arquebusiers to lay down a covering fire while another force struck the flank. Unfortunately for him, a sudden downpour doused the matches on his teppo. As soon as the rain stopped, the monks, who had covered their fuses during the storm, launched a counterattack. The volleys of fire decimated Nobunaga’s force, with one bullet narrowly missing him.
Oda Nobunaga finally defeated the Nagashima defenders in 1574 by allying himself with a force of pirate ships with cannon that destroyed the forts’ watchtowers and stopped any reinforcement by sea. After capturing two outer forts, Oda was able to surround the fort and fortified monastery and starve the monks out. He refused to accept their surrender and burned 20,000 starving defenders as well as locals who had fled to Nagashima before the attack. His final victory over the Ikko-ikki came in 1580, when he was able to capture and destroy the Honganji temple in Osaka.
Little in the campaigns against the warrior monks shows original tactical brilliance, but by facing the monks’ use of volley fire, Oda Nobunaga learned from it. Ironically, then, Nobunaga owed the Ikko-ikki armies a debt of gratitude, for it was they who taught him to be flexible in his fighting techniques and to adopt the volley fire as the most effective technique with the weapons.
