Kannō disturbance participant Ashikaga Tadayoshi
Resurgence of the Southern Court
The events
Takauji was nominally shōgun but, having proved not to be up to the task of ruling the country, for more than ten years Tadayoshi governed in his stead. The relationship between the two brothers was however destined to be destroyed by an extremely serious episode called the Kannō Incident, an event which takes its name from the Kannō era (1350–1351) during which it took place and which had grave consequences for the entire country. Trouble between the two started when Takauji made Kō no Moronao his shitsuji, or deputy. Tadayoshi did not like Moronao and his policies so (at least according to the  Taiheiki), after every effort to get rid of him failed, he tried to have him assassinated. Tadayoshi in 1349 was forced by Moronao to leave the government, shave his head and become a Buddhist monk with the name Keishin under the guidance of Zen master, poet, and old associate Musō Soseki. In 1350 he rebelled and joined his brother's enemies, the supporters of the Southern court, whose Emperor Go-Murakami appointed him general of all his troops. In 1351 he defeated Takauji, occupied Kyoto, and entered Kamakura. During the same year he captured and executed the Kō brothers, Moronao and Moroyasu, at Mikage (Settsu province). The following year his fortunes turned and he was defeated by Takauji at Sattayama. A reconciliation between the brothers proved to be brief. Tadayoshi fled to Kamakura, but Takauji pursued him there with an army. In March 1352, shortly after an ostensible second reconciliation, Tadayoshi died suddenly, according to the Taiheiki by poisoning.Effects
One of the main effects of the Disturbance was the re-invigoration of the war effort of the Southern Court.  To a large extent its renewed offensive was made possible by turncoats from the Muromachi regime.  The imperialist offensive of 1352 directed against Takauji in Kamakura was made possible by the vast numbers of former adherents of Tadayoshi who became supporters of the imperialist leader Nitta Yoshimune.  The imperialist offensive against Kyoto in 1353 was made possible through the defection of the shugo lord Yamana Tokiuji. Tadayoshi's adopted son Ashikaga Tadafuyu is an outstanding example of defection: he became the leader of the western armies of the Southern Court during the imperialist offensives against Kyoto in 1353 and 1354.
The end of the Disturbance on the other hand eliminated the sharing of power between the two Ashikaga brothers putting it all into Takauji's hands, strengthening his position and ultimately that of the early Muromachi shogunate as a whole.