Matsudaira Tadayoshi served as a bushō and daimyō during the Azuchi-Momoyama and early Edo periods.  Tadayoshi was the fourth head of the Tōjō-Matsudaira family and, in the Edo period, the lord of the Kiyosu domain in Owari Province.

Tadayoshi was born as the fourth son of Tokugawa Ieyasu and the younger brother of the same mother as Tokugawa Hidetada, the second shōgun of the Edo bakufu.  He was the son-in-law of Ii Naomasa, one of the Four Guardian Kings of the Tokugawa.

Tadayoshi was born as the fourth son of Tokugawa Ieyasu below Hamamatsu Castle in Tōtōmi Province.  In 1581, after Matsudaira Ietada, the third head of the Tōjō-Matsudaira family, died of illness, he inherited the headship of the clan along with Mikawa-Tōjō Castle and a fief of 10,000 koku.  He received one of the characters from each of the names of his father and his uncle, Matsudaira Hirotada, adopting the name of Tadayasu.  In 1582, he was transferred to Suruga-Numazu Castle with a fief of 40,000 koku.

From Tenshō 16 (1588) to 1/18 of Tenshō 18 (1590), in letters from Tokugawa Ieyasu, he expressed delight at a kosode, or short-sleeved kimono, received from Tadayoshi and admonished him to diligently pursue his studies.  These short exchanges reveal the close relationship between father and son, providing valuable insight into the manner of raising children in this period.

When Ieyasu was transferred to the Kantō, in 1592, Tadayoshi became the lord of Oshi Castle in Musashi and was granted a fief of 10,000 koku.  After his coming-of-age ceremony, he adopted the name of Tadayoshi.

In 1600, prior to the Battle of Sekigahara, Tadayoshi headed north for the Conquest of Aizu.  It is confirmed in a letter from Hidetada that, after arriving in Oyama, Tadayoshi advanced on the Tōkai Road in Suruga Province ahead of Ieyasu.  Based on this itinerary, he proceeded west prior to a war council held on 7/25 in Oyama.  At this meeting, known as the Oyama Deliberation, Ieyasu decided to return west toward Ōsaka to confront a rebellion launched by Ishida Mitsunari rather than continue north to confront Uesugi Kagekatsu.  Initially, Tadayoshi was assigned to guard Sunpu Castle, but upon the advice of Naomasa, he proceeded to Ōgaki in advance of Ieyasu.

At the main battle, under the watch of his father-in-law, Ii Naomasa, he fought in the vanguard along with Fukushima Masanori, winning the first contest.  Despite incurring injuries, he killed Shimazu Toyohisa among other contributions.  On the day after the battle, a letter from Yūki Hideyasu dated 9/25 sent in reply to a notice of victory from Naomasa noted that Tadayoshi served with honor.  Owing to Naomasa’s presence with Tadayoshi during the battle, the letter also refers to Naomasa’s honor and injuries.

After the war, on 11/18, Tadayoshi joined his older brother, Hidetada, on a visit to the Imperial palace and was invested with the titles of Junior Fourth Rank (Lower) and Chamberlain.  As recognition for his contributions, he was awarded a fief of 520,000 koku in Mino and Owari provinces whereupon he entered Kiyosu Castle.

In 1604, he learned the secrets of nōgaku, or traditional theater, from Shimotsuma Nakataka.  He then fell ill and, in the fifth month, went to an onsen, or hot springs, in Tajima Province to convalesce.  In the fourth month of 1605, he was conferred the title of Junior Third Rank and Lieutenant General of Imperial Guards for the Left Division.  In the tenth month he suffered from swelling and, in the twelfth month, became critically ill but, with medicine, recuperated.

In 1606, his appointed title of Governor of Shimotsuke changed to Governor of Satsuma.  On 4/16, he sent bamboo shoots via a close associate named Murakoshi Naoyoshi to Ieyasu who was en route to the capital.  So as not to harm the feelings of Ieyasu, he requested special attention be given when presenting gifts.  This also showed consideration toward Acha-no-tusbone (Unkōin), a consort of Ieyasu who managed the home.  It can be surmised that Tadayoshi feared his father at the same time that he cared for him.

In the fifth month, he convalesced in the Chita District but did not recover from his illness and, in 1607, went to Edo.  After meeting with Ieyasu and Hidetada, several days later, on 3/5, he died at the age of twenty-eight.  Four individuals including a bushi named Ogasawara Yoshimitsu martyred themselves.

Tadayoshi did not have a natural heir so his younger brother, Gorōta (Tokugawa Yoshinao) inherited the Kiyosu domain.  As a result, the Tokugawa Museum that keeps the treasured articles of the Owari-Tokugawa family also holds the armor of Tadayoshi.  Hidetada, his older brother born to the same mother, was anguished at the demise of Tadayoshi.

Character

As a handsome man with proper features and wide popularity, any lords all together would have no regret sacrificing their lives for Tadayoshi to serve him.

Tadayoshi’s armor matched well with the armor worn by his father-in-law, Ii Naomasa, and, owing to his service at the Battle of Sekigahara, similar to the Ii family, he was delegated command of the vanguard of the Tokugawa.