Born the son of Hōjō Ujiyasu, Sengoku daimyō based at Odawara castle in Sagami (Kanagawa). His great-grandfather was Hōjō Sōun (Ise Sōzui), and the Hōjō had spread their power widely across the Kantō. Because his elder brother died young, he was raised as heir.
As a pledge of the three-way alliance among the Hōjō, Takeda and Imagawa, he married Ōbaiin, daughter of Takeda Shingen. Their children included Ujinao, the future head of the clan.
His father Ujiyasu handed him the headship, and he became the fourth head of the Hōjō. Ujiyasu, however, kept real power for some time, and father and son governed together.
Uesugi Kenshin led the warriors of the Kantō to besiege Odawara castle, but the Hōjō held out inside its walls. From this time the strength of Odawara's defenses became widely known.
Takeda Shingen invaded the Imagawa lands in Suruga and the three-way alliance broke apart. His wife Ōbaiin is said to have been sent back to the Takeda, though some disagree. The next year the Hōjō made an alliance with Kenshin, their former enemy.
After Shingen besieged Odawara castle and then withdrew, the Hōjō army attacked him at the Mimase Pass, but was beaten by his skillful fighting.
His father Ujiyasu died. Ujimasa soon ended the alliance with the Uesugi and joined hands with the Takeda again. From then on he sent troops across the Kantō and widened his lands further.
After Kenshin's death a succession struggle broke out in the Uesugi house (the Otate Disturbance). Ujimasa's brother Uesugi Kagetora, whom Kenshin had adopted, fought the other adopted son Uesugi Kagekatsu, but was defeated the next year and lost his life.
He handed the headship to his son Ujinao, but kept real political and military power. Around this time the Hōjō lands spread over most of the Kantō, reaching their greatest extent.
When the Takeda fell and Nobunaga died in the Honnō-ji Incident, he fought Tokugawa Ieyasu over the former Takeda lands (the Tenshō Jingo War). They made peace, and Ujinao later married Ieyasu's daughter Tokuhime.
A Hōjō retainer seized Nagurumi Castle from the Sanada. Toyotomi Hideyoshi treated this as defiance of his orders and resolved to destroy the Hōjō. Ujimasa had kept putting off going to Kyoto to submit to Hideyoshi.
Odawara castle was surrounded by Hideyoshi's huge army, and after about three months of siege the Hōjō surrendered. Ujimasa and his brother Ujiteru took responsibility and ended their own lives, and Ujinao was sent to Mount Kōya. The Hōjō (the Later Hōjō), who had ruled the Kantō for nearly a century, came to an end.
Hōjō Sōun (Ise Sōzui)Hōjō UjiyasuTakeda ShingenUesugi KenshinTokugawa IeyasuUesugi KagekatsuToyotomi Hideyoshi
Ashikaga YoshiteruToyotomi HideyoshiAshikaga YoshiakiMaeda ToshiieAshikaga YoshihideImagawa UjizaneNabeshima NaoshigeHonda Masanobu
People of the Sengoku/Azuchi-Momoyama period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.