Jōkyū War participant Go-Toba
Jōkyū War (承久の乱, jōkyū no ran), also known as the Jōkyū Disturbance or the Jōkyū Rebellion, was fought in Japan between the forces of Retired Emperor Go-Toba and those of the Hōjō clan, regents of the Kamakura shogunate, whom the retired emperor was trying to overthrow.
The main battle was at Uji, just outside Kyōto; this was the third battle to be fought there in less than half a century. It took place in 1221, that is, the third year of the Jōkyū era.Background
In the beginning of the 13th century, Emperor Go-Toba found his attempts at political maneuvers blocked by the Kamakura shogunate. Seeking independence, and the power he considered rightfully his as the ruler of Japan, Go-Toba gathered allies in 1221, and planned to effect an overthrow of the shogunate. These allies consisted primarily of members of the Taira clan, and other enemies of the Minamoto, the victors in the Genpei War, and clan of the shōguns.Accounts of the first Imperial banner appear in this period, and the very first is said to have been one that Go-Toba gave to a general during this war.  Sun and moon images were embroidered or painted with gold or silver on a red brocade.