Isa Tamemune (伊佐為宗)

Tamemune ISA (year of birth unknown, died in 1221 [?]) was a gokenin (an immediate vassal of the shogunate in the Kamakura and Muromachi through Edo periods) who lived in the early Kamakura Period. He was also called Hitachi no kanja Tamemune. He held the post of kotaigu no Taijo (Senior Secretary of the household department for Empress). He called himself Isa Taijo.

Tamemune was a son of Hitachi nyudo Nensai, who was from the FUJIWARA no Yamakage line of the Northern House of the Fujiwara clan, also considered to be the founder of the Date clan. His honryo (main domain) was Isa County, Hitachi Province (present-day Chikusei City, Ibaraki Prefecture).

Tamemune's younger sister Daishin no Tsubone became a concubine of MINAMOTO no Yoritomo, and gave birth to a son (Jogyo).

In 1189, Tamemune took part in the campaign with his younger brothers Tameshige UENO, Suketsuna DATE, and Tameie DATE for the Battle of Oshu (Oshu-Seibatsu [Kamakura bakufu's military campaign against the Fujiwara of northern Japan]) launched by MINAMOTO no Yoritomo to hunt down and kill FUJIWARA no Yasuhira. On September 26, Tamemune's troops decapitated the heads of 18 enemies including Motoharu SATO, and gibbeted at Kyogaoka of Mt. Atsukashi after winning the Battle of Ishinazakahe to capture the foremost outpost fortress of the Oshu side situated in Shinobu County.

As a reward for the distinguished service in the Battle of Oshu, Yoritomo granted Date County to the family of Tamemune ISA. While Tamemune stayed in Isa County (Hitachi Province), Nensai and Tamemune's younger brothers moved to Date County and called themselves as 'Date' to be the founder of Date clan.

In 1221, he fought in the Jokyu War and died in the Battle of Uji-gawa River.