Thought to have been born in Bitchū (Okayama) into the Ise, a family of Muromachi shogunate officials (some say born 1432; debated). His real name was Ise Moritoki; "Hōjō Sōun" is a later name.
His sister Kitagawa-dono was the wife of Imagawa Yoshitada of Suruga. When Yoshitada died in battle and a succession dispute arose, he reportedly went to Suruga to mediate.
Around this time he served the 9th shogun Ashikaga Yoshihisa in Kyoto as an intermediary official, and also studied Zen.
Returning to Suruga, he struck down Oshika Norimitsu, who had seized power in the Imagawa house, and made his nephew Ujichika head of the Imagawa, receiving Kōkokuji castle as reward.
He attacked Ashikaga Chachamaru, the Horikoshi deputy of Izu, and seized the province (year debated). Taking a province by ability rather than lineage, he is cited as an example of gekokujō heralding the Warring States era.
He took Odawara castle in Sagami from the Ōmori, a foothold for advancing into the Kantō (year debated). Odawara later became the seat of five generations of the Hōjō.
He pacified Izu and reportedly governed with care for his people, for example lightening the tax on harvests. The "Twenty-One Articles of Sōunji-dono", a code of conduct for retainers, is attributed to him.
He destroyed the Miura of the Miura Peninsula at Arai castle and took all of Sagami.
He passed headship to his son Ujitsuna, from whose time the family used the name Hōjō; they are called the Later Hōjō to distinguish them from the Kamakura Hōjō.
He died at Nirayama castle in Izu. The Hōjō went on to dominate the Kantō for some seventy years.
Amago TsunehisaHojo UjitsunaSaitō DōsanTaigen SessaiMōri MotonariFrancis XavierŌuchi YoshitakaMatsunaga Hisahide
People of the Sengoku/Azuchi-Momoyama period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.