act. It may be that Tsunehisa became aware of Motonari's talent and wary of his expansion, for from then on a rift would grow between Tsunehisa and Motonari. Early Rise Leadership of the Mōri clan In July 1523, Motonari's nephew Kōmatsumaru, the titular head of the clan, died suddenly at the age of nine. The senior Mōri vassals met and decided to offer the leadership to Motonari and on August 10 he entered Yoshida-Kōriyama Castle as its new lord. However, some among the senior vassals dissented from the decision and in 1524 any sense of security was broken when Mōri suffered the defection of his vassal Katsura Hirozumi (桂広澄), and was forced to defeat the traitor in open battle not far from Yoshida-Kōriyama Castle. Also in 1524, Motonari learned of a conspiracy led by a vassal, Sakagami Sosuke, to murder him and elevate his half-brother Aiō Mototsuna to the leadership. The rebellion was crushed at Funayama Castle in April. Service under Ōuchi clan Along with the family troubles concerning succession, Motonari and Amago Tsunehisa gradually grew hostile towards one another. In March, 1525 Motonari and several other local lords decided to change allegiance to Ōuchi Yoshioki. In June, Yoshioki sent his army to Kagamiyama Castle and took it from the Amago clan. Considering Kagamiyama's weak defenses on a low hill, Yoshioki built a new castle called Tsuchiyama Castle at the western edge of Saijo Basin on a high mountain and demolished Kagamiyama. In 1529 Yoshioki died and was succeeded by his son Ōuchi Yoshitaka. Amago Tsunehisa began negotiating with Takahashi Okimitsu (高橋興光), a maternal relative of the late Mōri Kōmatsumaru who had earlier schemed to place Motonari's brother, Aiō Mototsuna, as head of the Mōri clan. Motonari acted quickly and crushed the Takahashi clan, taking their vast territory from Aki Province to Iwami Province. He paid a high price for the conquest, however, because Motonari's eldest daughter had been a political hostage of the Takahashi clan and was murdered by them in revenge. A rebellion broke out against the Ōuchi clan in 1532; in response, thirty-two vassals presented Motonari with an oath in which they sought a guarantee that he would not require them to give up their status as small-scale lords, in return for which they promised to jointly undertake the repair of walls and irrigation ditches and the disciplining of traitorous vassals. On September 25, 1533, Motonari was