Late medieval Japan witnessed increasing activities by large groups of armed organized peasantry, culminating in the massive peasant movements of the Sengoku Era. When these hordes resorted to raping, pillaging, and looting, they were usually deemed akuto, or "evil bands," but when they were more organized and orderly, they were termed ikki, or "leagues." Foremost among these "leagues" of armed peasants was the so-called Ikkô Ikki or "Single-minded League."
Like many of the largest ikki, the Ikkô Ikki emerged in the chaos and collapse of social order that followed in the wake of the Onin War (1467-1477). The Ikkô Ikki developed within the Honganji branch of the Jodo Shin sect of Pure Land Buddhism, and soon grew into one of the most powerful military forces in all of Japan. Strict adherents of the original teachings of Jodo Shin founder Shinran (1173-1262), the Honganji branch of the sect took its distinctive form under Kakunyo (1270-1351). Unique to the Honganji sect, and crucial to its later power, was its emphasis on regional organization under local leaders at the village level, and an almost complete autonomy from the traditional monastic, military, and court hierarchies. With the arrival of the total chaos of Sengoku, these two features put the Honganji sect in a unique position to reach for vast power, because they could quickly recruit vast armies of peasants, and they could not be controlled by anyone. The result was the mighty Ikkô Ikki.
In just a few short decades, the Ikkô Ikki warriors became legendary for their utter fearlessness in battle and soon the appearance of the fluttering white banners of the Ikkô Ikki on the field of battle was enough to put a quake in stomach of even the bravest of samurai. The Ikkô Ikki was made up largely of armed peasants, low ranking samurai, and jizamurai (warrior-peasants ranking below the bushi but above ordinary villagers) - the classes of people most disposessed by, and least able to cope with the social disorder. Their utter fearlessness came almost as much from the fact that they had nothing to lose as from the Jodo Shin promise that anyone who died in battle chanting the name of Amida would be reincarnated in the Pure Land western paradise. It was that potent mixture of utter dispair and a tiny shard of hope that all great uprisings are built on.
In battle the Ikkô Ikki were a mess. Poor villagers armed with whatever makeshift weapons and tattered, recyled armor they could lay their hands on, they had no training in any real sense, and thus any sort of organized tactics were out of the question. Usually they just marched ahead in a straight line in the direction they were pointed by their commanders and got slaughtered until they overwhelmed their highly trained samurai enemies with sheer numbers. But as ragtag as they must have looked, what an awesome sight it must have been to see thousands of men marching in rows, their signature hand-painted Buddhist slogans fluttering on banners and from their spears and emblazoned on their white headbands. And of course there was the unearthly drone of their chanting, as thousands of throats recited the mind-numbing sutras, putting themselves in the trancelike state that allowed them to be oblivious to pain and to die by the cartload.
No one is sure when exactly the Ikkô Ikki first originated out of its misty Honganji origins, but already by 1488 the league was strong enough to defeat the powerful shugo of Kaga province, Togashi Masachika. For the next century, the Ikkô Ikki ruled Kaga province in lieu of daimyo, and set about increasing their landholdings throughout Japan. By the late 1500s the Ikkô Ikki had powerful branch organizations all over central Japan and controlled vast territories from at least 15 massive temple-fortresses. Ultimately however, the Ikkô Ikki's might and autonomy made it too dangerous, and the league finally fell when Oda Nobunaga made its complete destruction his personal obession. Nobunaga viewed the Ikkô Ikki as vermin, and gave no quarter, going out of his way to slaughter as many of its members as he could. He felt no compunction doing things like burning thousands of trapped Ikkô Ikki warriors alive inside a surrounded fortress, killing any who tried to leave or surrender, and whenever he wasn't distracted fighting other warlords, he would again return to smashing the Ikkô Ikki. It took him over ten years, but at last Nobunaga broke the power of the league when he destroyed the Ishiyama Honganji (now Osaka Castle) in 1580, and the last Ikkô Ikki fortress was captured and razed by Nobunaga's successor, Toyotomi Hideyoshi, in 1583. After a century-long reign of terror, the Ikkô Ikki had finally met a force more single-minded than itself.