Tamura Akiyori served as a bushō during the Sengoku and Azuchi-Momoyama periods.  He was a retainer of the Tamura clan.

Akiyori was born as the second son of Tamura Moriaki, the twenty-second head of the Tamura.  His older brother was Tamura Yoshiaki.  Akiyori is also known by his monk’s name of Gessai.

An important figure in the Tamura family, Akiyori served Yoshiaki’s eldest son, Tamura Takaaki, the twenty-fourth head of the clan.  Later, he served Takaaki’s son, Tamura Kiyoaki.  In battle, he served as a strategist.  Akiyori excelled in military planning.  Feared by surrounding clans, he was referred to as Gessai the Attacker or by the phrase, “If you have creeping lettuce in the vegetable fields, pondweed in the rice fields, and Gessai in the Tamura, then all is good.”

In Akiyori’s era, gōzuku, or wealthy families, in the area aligned with the  Ashina.  The Tamura, however, joined with the Satake in opposition to the Ashina, causing strife for the clan.  In 1559, Akiyori joined Takaaki in an assault against the Nikaidō clan, toppling Imaizumi Castle.  He then became the chamberlain of the castle.

Thereafter, the Tamura clan changed direction and joined with the Ashina to attack the Satake.  In 1571, he repelled an attack by Satake Yoshishige on the Nametsu manor.  In 1574, his nephew, Takaaki, died so, thereafter, he served as a deputy to his great-nephew, Tamura Kiyoaki.  After the Ashina and Satake reconciled, the Tamura were encircled by enemies.  In 1579, Kiyoaki’s daughter, Megohime, wed Date Masamune.  After this time, the Tamura joined with the Date in battles against the Nikaidō.

Within the Tamura family, Akiyori was a powerful figure in the faction supporting the Date, but the overbearing exercise of authority by this faction triggered internal conflict.  For a while, Masamune considered expelling Gessai.  The family disturbance following the death of Kiyoaki caused Masamune to take measures in an event known as the Tamura Retribution.

In 1586, Kiyoaki suddenly died, marking a series of deaths of the head of the clan including Akiyori’s father, older brother, nephew, and great-nephew.  Kiyoaki did not have an heir.  In his will, he stated that if Masamune and Megohime have a child, then have the child become his adopted successor.  Nevertheless, Kiyoaki’s widow (the daughter of Sōma Akitane) sought to have a member of the Sōma family become the successor.  This resulted in a succession struggle known as the Tenshō Tamura Disturbance.  Nevertheless, Gessai continued to align with the Date.

In 1588, Sōma Yoshitane sought to enter Miharu Castle, but Akiyori, backed by Masamune, rained gunfire on Yoshitane and his men to halt them.  During this clash, he shot and killed a retainer of the Sōma known as Ei Taneharu.  Later, he worked to enable Masamune to enter Miharu and succeeded in expelling elements of the opposing faction.

In 1589, Akiyori participated in a siege by the Date clan of Sukagawa Castle held by the Nikaidō clan.

The Tamura clan, however, did not participate in the Conquest of Odawara led by Toyotomi Hideyoshi.  During the ensuing Oushū Retribution, the clan was removed from their position as a daimyō family.

Note regarding age

Akiyori’s father, Moriaki, is believed to have died in 1487, and, even if Akiyori was born around this time, during the siege of Sukagawa Castle, he would have been over one hundred years old, which is inconsistent with the noted year of his birth.  Therefore, there is a theory that the name of Gessai may have been used by two individuals in succession.