People usually think of the medieval peasant as miserable and downtrodden, but the peasants of sixteenth century Germany had managed to become fairly prosperous and no longer expected to be treated like serfs. When a series of complex economic and political changes began to erode their hard-won position, they didn't take it lying down. Instead they went to war, staging a series of massive rebellions against the feudal order between 1524 and 1526.
300,000 people are thought to have been involved in the Peasant's War, which was largely confined to the German areas of the Holy Roman Empire. 100,000 are thought to have lost their lives, and atrocities were committed by both sides.
In the end, as is usually the case with peasant rebellions, the rebels lost. However, they did succeed in inflicting a number of defeats on armies composed of and commanded by their supposed betters- just like the ikko-ikki peasant rebels in medieval Japan.
Interestingly, there is another parallel with the ikko-ikki. Both sets of rebellious peasants had the custom of gathering in a ring or circle to emphasize the equality of the rebel fighters. The German peasant rebels made at least some of their tactical decisions democratically. It's an interesting aspect of the peasant rebellion as a historical phenomenon- in many cases the rebels actually did present a more democratic and equal alternative to the feudal order. In a way, it can even be compared to the General Assembly meetings used by today's Occupy protesters to make decisions through consensus.