In the late 12th century, simmering intrigue at the imperial court boiled over into what would come to be known as the Genpei War (1180-1185), a monumental clash between two rival clans, the Taira and the Minamoto. The war wrought incredible havoc upon the very foundation of Japanese society, removing political rule from the emperor, placing it with the shogun, and initiating quintessential samurai tropes. Anecdotes from these battles have been reenacted in theater, literature, and art since that time.
Although physical force on the battlefield was important to the feuding clans and is celebrated in these prints, this was a period in which Machiavellian politics and intricate strategy became indispensable to fighting a successful war. The idea of loyalty, while important, was complicated by intense individual ambitions; warlords defected from the emperor's rule for their own personal gain and brothers betrayed each other in fear of undesirable competition.
During this period, the ideal of dying honorably became a value of central importance for warriors. The first act of seppuku ritual suicide committed by slicing open one's bowels with a short sword was recorded in this period, and this would come to be the death of choice for heroic warriors in the future. Seppuku was often committed to avoid the humiliation of being killed by the enemy.