<論説>足利義教期の対関東政策

Abstract

本稿は、永享の乱に至る室町幕府と鎌倉府の関係を、足利義教の対関東政策に着目して再考したものである。義教は、鎌倉府の征討を一貫しては志向せず、鎌倉府との和睦が可能になると、鎌倉公方足利持氏との関係修復を基軸に、両府関係を展開し、上位者たる自らの勢威のもとでの融和策を企図した。持氏も、永享三年の和睦以降、義教に恭順を示した。しかし、対関東政策の負の側面によって、鎌倉府で不穏な噂が現れるなかで、鎌倉公方の存立に関わる雑説も発生し、持氏は東国支配への危機感を徐々に強め、鎌倉公方の地位も左右されない一元的な東国支配をめざした。持氏がかかる政治的志向を強めたことで、関東管領と奉公衆、持氏と関東管領の間で、鎌倉府の政治方針や支配体制をめぐる深刻な対立を惹起させた。結果、持氏は、義教の政治的求心性や融和策を否定する行為を断行し、義教の和平戦略を破綻させ、義教は持氏攻撃に踏み切ったのである。

This paper reexamines the relationship between the Muromachi Shogunate and the Kamakura-fu in the period leading up to the Eikyō Rebellion by focusing on the Shogun Ashikaga Yoshinoriʼs policy toward the Kanto region. Much of previous scholarship has understood Ashikaga Yoshinori as being intent on subjugating the Kamakura-fu. However, when peace with the Kamakura-fu became possible, Yoshinori developed the ties between the Muromachi shogunate and the Kamakura-fu by repairing relations with the Kamakura Kubō Ashikaga Mochiuji. Yoshinori sought to build the relationship with Kamakura-fu by implementing a policy toward the Kanto region that combined hardline measures exercised by himself to subjugate Mochiuji and reconciliatory measures to stabilize relations with the Kamakura-fu through the Kantō Kanrei Uesugi Norizane. Mochiuji also demonstrated fealty to Yoshinori after the establishment of peace in the 3rd year of Eikyō (1431). However, Yoshinoriʼs policy toward the Kanto region also had aspects that caused friction between Kyoto and Kamakura. These negative aspects of the Kanto policy led to unsettling rumors within the Kamkura-fu about discord between Kyoto and Kamakura. Under such circumstances, rumors arose regarding the continued existence of the Kamakura Kubō, and as Mochiujiʼs sense of crisis about the rule of Tōgoku gradually strengthened, he sought to rule without interference from the shogunate. As Mochiuji strengthened his political orientation, the conflict with the Kanto Kanrei Uesugi Norizane, a direct vassal of the Kamakura Kubō, and the Hōkōshū, became more serious. This created a wide gap between Mochiuji and Norizane over the system of rule in the Kamakura-fu. As a result, Mochiuji decided to act to block both the power of Yoshinori, who was his lord, and that of Uesugi Norizane, who was the key to Yoshinoriʼs stabilization measures, and destroy Yoshinoriʼs peace strategy. The Kanto policy proposed by Yoshinori was thus wrecked by Mochiuji. This was the background to the decision that transformed Yoshinoriʼs policy into one of confrontation with the Kamakura-fu. Yoshinori intended to exert shogunal power in the Kanto region and to have one of his sons become Kamakura Kubō. Yoshinori intervened in the Kanto region with the aim of establishing a system whereby the Kamakura-fu would be under his strong control, led by his son and Norizane, and obedient to Kyoto. Thus, in the 10th year of Eikyō (1438), the Eikyō War broke out.