Lifespan: Keichō 9 (1604) to 8/18 of Kanei 11 (1634)
Rank: bushō, daimyō
Title: Junior Fifth Rank (Lower), Senior Assistant Minister of Central Affairs, Senior Fourth Rank (Lower), Chamberlain
Domain: Head of Dewa-Kaminoyama, Head of Iyo-Matsuyama
Lord: Tokugawa Iemitsu
Father: Gamō Hideyuki
Siblings: Tadasato, Tadatomo, Sūhōin (daughter of Gamō Hideyuki)
Wife: Seventh daughter of Naitō Masanaga
Gamō Tadatomo served as a daimyō during the early Edo period. He was the head of the Kaminoyama domain in Dewa Province. Later, he became the head of the Matsuyama domain in Iyo Province. His true name was Tadachika.
In 1604, Tadatomo was born as the second son of Gamō Hideyuki, the head of the Mutsu-Aizu domain. He was raised by a retainer of the family named Gamō Satoharu. Asano Mitsuakira was a younger brother of a different father.
In 1612, Tadatomo was given the Matsudaira surname. In 1626, he became the head of the Dewa-Kaminoyama domain with a fief of 40,000 koku.
In 1627, Tadatomo’s older brother, Gamō Tadasato (the head of the Aizu domain) died earlier without an heir so that naturally would have been the end of the Gamō clan, but because his mother, Shōsei-in, was the daughter of Tokugawa Ieyasu, the Edo bakufu allowed Tadatomo to inherited the headship of the family. The domain was reduced and transferred from Aizu with a fief of 600,000 koku to Iyo-Matsuyama with a fief of 240,000 koku. Nevertheless, perhaps owing to the influence of his faithful formal wife, good governance, or projects such as the construction and relocation of temples, he made notable contributions while managing the domain. In particular, he put effort into completing the construction of his base at Matsuyama Castle, developing the outer citadel.
In 1630, Tadatomo addressed a dispute that arose again with senior retainers; however, the matters at issue could not easily be resolved for three (3) years, so Tadatomo aimed for the bakufu to render a verdict and finally attain a resolution. As a result, not only were elders from the Fukunishi, the Seki, the Oka, and the Shiga ousted or exiled, the chief retainer named Gamō Satoie was put on leave and called out from among many to face consequences.
In the Edo period, daimyō were required to alternate between Edo and their home provinces in service to the Edo bakufu. In 1634, while traveling for official attendance service, Tadatomo suddenly died in the Kyōto residence for his domain. He was thirty-one years old. Although uncertain, he may have died from smallpox as did his older brother, Gamō Tadasato. He did not have an heir so his demise brought an end to the Gamō family. Owing to Tadatomo’s death, the Ōmi-Gamō lineage ended, but there was talk among residents that divine punishment served as the underlying cause.
There is a portrait of Tadatomo handed-down over generations in the Iyo-Enpuku Temple in Matsuyama.
Anecdotal horror story
After Tadatomo became the head of the domain, a long time passed without the birth of a male heir, but soon he directed his resentment toward pregnant women in the domain, apprehending and killing them and their unborn children in a repeated series of tragic events. It was said that the hatred of pregnant women who met untimely deaths culminated in the end of the Gamō family. As evidence, there is a stone cutting board in Matsuyama Castle, and in the park built on the castle ruins, one can still hear the sound of sobbing. This type of story can also be heard, among others, with respect to a well at Himeji Castle where a consort of Kodera Norimoto named Okiku had been killed and abandoned.