Throughout the long history of the samurai class, warriors were involved in many different types of conflicts, even battling armies of discontented warrior monks from militant Buddhist monasteries from time to time. By far the most common type of conflict, however, was interclan fighting, which grew not only more intense in the sixteenth century, but also more widespread as weapons and combat tactics changed.

After Minamoto Yoritomo came to power, he established a stable form of government called the bakufu. When Yoritomo died, his widow, Lady Masako, along with members of her own clan (the Hojo family), became the power behind the bakufu government.

Acting as regents to the shoguns, the Hojo family ruled behind the scenes for over a century, but were eventually toppled by the Ashikaga clan in 1338. Although the Ashikaga shoguns were literate men and patrons of...