thumb|Ashikaga Tadayoshi depicted in an Edo period print
was a Japanese samurai general of the Northern and Southern Courts period (1337–92) of Japanese history and a close associate of his elder brother Takauji, the first Muromachi shōgun. Son of Ashikaga Sadauji and Uesugi Kiyoko, daughter of Uesugi Yorishige, the same mother as Takauji, he was a pivotal figure of the chaotic transition period between the Kamakura and Muromachi shogunates. Tadayoshi is today considered a military and administrative genius and the true architect of many of his elder brother's successes. In contemporary chronicles he is rarely called with his name, but is instead called either or from the name of his family temple.
Biography
The Ashikaga were a samurai family from Kamakura having blood ties with the Seiwa Genji, Minamoto no Yoritomo's clan. Unlike his brother Takauji, Tadayoshi took no part in the Kamakura shogunate's political activities until the Genkō War (1331–1333), a civil war whose conclusion (the Siege of Kamakura (1333)) marks the end of the Kamakura period and the beginning of the most turbulent period in Japan's history, the Muromachi era. The samurai class as a whole however was not ready to give away power, so the alliance between him and the Ashikaga was bound to be only temporary.
Go-Daigo wanted to re-establish his rule in Kamakura and the east of the country without sending there a shōgun, as this was seen, just a year from the fall of its shogunate, as still too dangerous. The appointment of a warrior to such an important post was intended to demonstrate the Emperor that the samurai class was not ready for a purely civilian rule.
In Dec. 1335, Tadayoshi was defeated by imperial forces under the command of Nitta Yoshisada forcing his retreat to the Hakone mountains. However, with the aid of his brother Takauji, they were able to defeat Yoshisada at the battles of Sanoyama and Mishima. The brothers were then free to advance upon Kyoto.
Dividing power between them, Takauji took charge of military affairs and Tadayoshi of judicial and administrative matters.
Both Tadayoshi and Takauji were disciples of famous Zen master, intellectual and garden designer Musō Soseki, under which guidance the first would later become a Buddhist monk.
In 1351 Tadayoshi rebelled and joined his brother's enemies, the Southern court, whose then emperor, Go-Murakami appointed him general of all his troops. In 1351 he defeated Takauji, occupied Kyoto, and entered Kamakura. During the same year his forces killed Moronao and his brother Moroyasu at Mikage (Settsu Province). The following year Tadayoshi's fortunes turned and he was defeated by Takauji at Sattayama. The temple was founded on the grounds of Tadayoshi's former Kamakura residence, according to Jōmyō-ji's own records by Tadayoshi himself. According to the , the diary of priest Gidō Shūshin, in 1372 on the day of Tadayoshi's death Kamakura's Kubō Ashikaga Ujimitsu visited Daikyū-ji.