Hōjō Ujiyasu was the son of Hōjō Ujitsuna and a daimyō of the Odawara Hōjō clan. His only known wife was Imagawa Yoshimoto's sister, Zuikei-in.
Early years and rise
His childhood name was Chiyomaru. He fought his first battle when he was fifteen years old, facing Uesugi Tomooki of the Ōgigayatsu Uesugi clan at the Battle of Ozawahara in 1530. Upon his father's death in 1541, a number of the Hōjō's enemies sought to take advantage of the opportunity to seize major Hōjō strongholds. Two Uesugi factions united with the Koga Kubo cause and attacked Kawagoe in 1542 in a night engagement still celebrated in Japanese military annals. "The result was the complete defeat of the Uesugi forces and the Koga contingent. From that date the Go-Hōjō as they were called, went on to further triumphs, beginning with the destruction of the Uesugi family."
Conflict with Uesugi
, the eldest legitimate son of Uesugi Tomooki, tried unsuccessfully to take Edo Castle following his father's death in 1537. In 1545, Tomosada allied himself with Ashikaga Haruuji and Uesugi Norimasa of Yamauchi Uesugi clan and besieged Kawagoe Castle. Hōjō Tsunashige, the stepson of Ujiyasu's brother Tamemasa and son-in-law of Ujitsuna, was outnumbered 3,000 to allegedly 80,000, and Ujiyasu led a relief force of 8,000 soldiers. Ujiyasu slipped some samurai past the enemy lines to inform Tsunashige of the enemy's approach, and made use of ninja to learn of the enemy's strategy and attitude. Using this intelligence, he led a night attack against the Ashikaga-Uesugi forces which is now said to be the one of the most notable examples of night fighting in samurai history. Despite being vastly outnumbered, the Hōjō army defeated the besiegers because, under Ujiyasu's orders, they were not bulked down by heavy armor, and were not slowed by seeking to take heads. This victory marked the decisive turning point in the struggle for the Kanto, and in the following years, proved the end of the Ōgigayatsu Uesugi line and destroyed the prestige of Norimasa of the Yamanouchi Uesugi clan as the Governor-General of Kantō region. In 1551, Ujiyasu defeated Uesugi Norimasa at Hirai Castle and forced him to flee to Echigo, where he was taken into the protective custody of his retainer Nagao Kagetora, the later day Uesugi Kenshin and heir to Norimasa by adoption. In 1561, Kenshin assumed the post of Kantō kanrei and in the same year, Kenshin besieged Odawara Castle, Hōjō's home castle, and burned down the town of Odawara. Kenshin then withdrew after two months.
Hōjō expansion
Allied with Takeda Shingen, a combined army of Hōjō and Takeda regained Musashi-Matsuyama Castle in Musashi Province against Uesugi Norikatsu in 1563. Hōjō Ujiyasu expanded the Hōjō territory, which now covered five provinces, and managed and maintained what his father and grandfather had held. He took Kōnodai in Shimōsa Province in 1564 following a battle against Satomi Yoshihiro . Following this victory, Ujiyasu pushed on into Shimosa Province and Kazusa Province, but was never able to destroy the Satomi clan, who remained a thorn in the Hôjô's side right up until 1590. Ujiyasu's eastern moves brought the Hôjô into conflict with the Satake clan of Hitachi Province and to the limit of their expansion. After second battle of Konodai, the Hôjô largely contented themselves with ruling the vast tracts of land earned through 60 years of war and toil.
Conflict with Takeda
Towards the end of his life he saw the first major conflicts between his own clan and Takeda Shingen, who would become one of the greatest warlords of the period. As a response to Hōjō's intervention in his invasion of Suruga Province, Shingen came into Musashi Province from his home province of Kai, attacking Takiyama and Hachigata Castles, where Ujiyasu's sons repulsed them. Despite the intact castles behind him, Shingen pressed on to the Hōjō central home castle of Odawara, burning the castle town and withdrawing after three days. As the forces of Takeda Shingen withdrew from repeated failed sieges of Odawara Castle, two of Ujiyasu's seven sons, the brothers Ujiteru and Ujikuni, attacked him in the pass of Mimase, ending the first of the Takeda campaigns against the Hōjō. Later in the year, Shingen's son Takeda Katsuyori led a successful siege against the Hojo Kanbara Castle in Suruga province. Takeda Shingen also laid siege to other Hōjō holdings in the surrounding provinces, including Fukazawa castle in Suruga province which was taken in 1571.
Death
Subsequently, Ujiyasu managed to make peace with Uesugi Kenshin and Takeda Shingen, the most powerful adversaries of Hōjō Ujiyasu, letting his seventh sonHōjō Saburō be adopted by childless Kenshin and accepting the fait accompli of Shingen's reign over Suruga. To cement the ties of Takeda-Imagawa-Hojo, Ujiyasu also gave his two daughters to those two clans; Lady Hayakawa wed to Imagawa Ujizane, while Lady Hojo wed to Takeda Katsuyori becoming his second wife. Ujiyasu died in 1571, passing on the Hōjō domains to his eldest son Ujimasa in a relatively favourable situation.
