Koga Castle – Chris Perry, Author

Historians disagree on when the Sengoku Jidai actually began, with the Onin War being a common origin point. The other possibility is our subject today, the Kyotoku Rebellion.

You may remember that the Kanto, the area in and around modern Tokyo, was not directly ruled from Kyoto. Instead, a member of the Ashikaga Family (from a different branch to the Shogun’s line) served as the Kamakura Kubo, a governor who effectively ruled independently from Kamakura, the capital of the previous Shogunate.

The kubo didn’t rule alone, however, he was nominally supported by the Kanto Kanrei, the Shogun’s direct deputy in the region, a position that was supposedly subject to direct appointment by the Shogun, but had in reality become a hereditary title of the Uesugi Clan.

Both positions were supposed to be loyal to the Shogun in Kyoto, but within a few years, that had become a legal fiction. The Kubo was formed in 1349, and for a while, records show them deferring to the central government in most things, especially the all-important appointments of provincial governors (shugo).

We’ve covered the details of the individual flashpoints in earlier posts, but to recap very briefly, in 1416, 1438, and 1440, there was a series of escalating conflicts that pitted the kubo against the Shogun. After 1440, the Shogun, at this point Ashikaga Yoshinori, sought to take control of the Kanto directly, and the Uesugi were happy to oblige. The position of kubo was abolished, and the Uesugi ruled with an iron fist, certain of the Shogun’s support.

Ashikaga Yoshinori, who supported the Uesugi in the Kanto.

This support largely relied on the Shogun being alive, however, and when Yoshinori was assassinated in 1441, the situation in the Kanto grew tense very quickly. In response, the Shogunate government acquiesced to a petition from several Kanto lords, requesting a new kubo.

This was granted, and Ashikaga Shigeuji was appointed in 1449. This, however, did not please the Uesugi, especially after Shigeuji began to distance himself from working with them, favouring the clans that had supported his father, Mochiuji.

In April 1450, things came to a head when supporters of the Uesugi attacked the kubo at his residence in Kamakura. Caught by surprise, the kubo was forced to flee to nearby Enoshima, where he regrouped and defeated the Uesugi forces when they pursued him.

Although the head of the Uesugi (and kanrei), Noritada, had not been directly involved in the attack, he took responsibility and was confined to house arrest. It was at this point that a new problem arose. As I mentioned, prior to 1440, the kubo had operated largely independently of the Shogun, but after the position was restored, the central government intend to keep Kamakura on a much shorter leash.

Part of this leash shortening involved the insistence that any formal request to the Shogun required the signature of both the kubo and the kanrei. The problem now was that Noritada was under house arrest, and in an uncooperative mood, effectively leaving Shigeuji with no way to (legally) govern.

Shigeuji was eventually forced to release Noritada, but the conflict between the two would only get worse. On the one hand, Noritada was head of the powerful Uesugi Clan, and kanrei, appointed by the Shogun, and his goal was to preserve the power and dignity of his family and their position in the Kanto.

Shigeuji, on the other hand, appears to have had more personal reasons. Although there’s no doubt his position as kubo required a certain ruthlessness, sources from the time suggest that Shigeuji blamed the Uesugi for the death of his father, and he was consumed by a desire for revenge.

So it came to pass, in December 1455, Shigeuji issued orders summoning Noritada to his residence. There’s a fair amount of speculation as to why Noritada would agree to go, given that it appeared to be an obvious trap, but go he did, and shortly after he arrived, he was cut down by men loyal to Shigeuji.

This assassination was accompanied by similar acts across the Kanto, as Shigeuji’s supporters moved to cut the head off the proverbial snake. The Uesugi Clan was vast, however, like most major clans, it had branches all over the country, and Noritada’s brother and heir had actually been in Kyoto when he was assassinated, meaning that his succession as kanrei, at least on paper, went off with minimal interference.

The other branches of the Uesugi Clan were enraged by Noritada’s death, and it wasn’t long before the new kanrei was able to gather an army and establish himself at Hirai Castle in Kozuke Province (modern Gunma Prefecture). When they marched against Kamakura, however, they were defeated at the Battle of Bubaigawara in modern-day Fuchu.

The Uesugi were forced to retreat and ended up under siege at Oguri Castle, in modern-day Ibaraki Prefecture, and a long way from Kamakura. This proved to be a problem for Shigeuji, for although he was able to take Oguri Castle, forces sent by the Shogunate (who were none too pleased about Shigeuji’s actions) took Kamakura from behind (stop laughing), cutting the Kamakura Kubo off from Kamakura. From then on, Shigeuji would base himself at Koga Castle and became known as the Koga Kubo. We’ll just keep calling him kubo, though.

The war between the Kanto’s two most powerful figures naturally led to utter chaos. Although both the kanrei and kubo could command the loyalty of thousands of warriors, the reality was that, with central power non-existent, rival clans took to settling their own affairs, usually at swordpoint.

With neither side able to establish control, the Shogun dispatched his brother, Ashikaga Masatomo, to the Kanto in December 1457, officially to be the new Kamakura Kubo. This didn’t work as planned, however, Masatomo only had the power his brother would allow him, and the Kanto lords knew it.

It got so bad that Masatomo couldn’t even take up residence in Kamakura and ended up at Horikoshi, in modern-day Shizuoka Prefecture. This situation led to him being called the Horikoshi Kubo, another would-be master of the Kanto who wasn’t even strong enough to demand his original title.

Things got even worse when the Shogun attempted to launch a punitive expedition against Shigeuji. Even before the forces were properly gathered, the leader of the army, a member of the Shiba Clan, was expelled from his post after dispatching troops from the expedition to his own province (far to the north of the Kanto) to deal with private battles there.

With the debacle of the expeditionary force, any hope for a decisive end to the war was lost, and the two sides got bogged down in back-and-forth skirmishes, sieges, and other militaristic shenanigans, with the (very loose) border being the Tone River, in the central Kanto.

A later depiction of a canal entering the Tone River

This would go on for ages, one side would gain the advantage, only to lose it again later and then suffer counter-attacks that would be themselves defeated. In 1466, the kanrei was killed in battle, and Shigeuji’s forces were briefly in the ascendance, but the Uesugi would recover, and in 1468, they would launch several successful counterattacks, and later, in 1471, they would even capture Shigeuji’s base at Koga.

You might think that Shigeuji would be on the ropes, but no, he struck back, recaptured Koga, and the war dragged on, and on, and on. Just as the Onin War destroyed central authority in and around Kyoto, the Kyotoku War, which had now raged for 16 years, did the same in the Kanto.

Then, in 1478, after 21 years of war, the Uesugi, suffering a major internal rebellion, were compelled to seek peace with Shigeuji, and the kubo, facing problems of his own, agreed. This ended the main phase of the war between the major powers, but did not bring peace to the Kanto, as both the Uesugi and Shigeuji turned to dealing with internal matters, putting down rebellions and forcing obedience from their erstwhile vassals, which is rarely a peaceful process.

A final peace would be agreed in 1483 (yes, five years after the initial proposals), and Shigeuji was allowed to continue as kubo; however, he was forced to hand over Izu Province to Masatomo, who continued as Horikoshi Kubo.

I’m sure, if you think about it for a moment, having two kubo in the Kanto region was never going to last, and it didn’t. Shigeuji had the authority and military power, but Masatomo had the legitimacy of Shogunate support; it was not a recipe for stable and secure government.

While the fighting had been going on in the Kanto, the Onin War had started and ended (1467-77), and Shogunate authority was effectively at an end. This meant that actual support for Masatomo was minimal, and historians suggest that the only reason Shigeuji and the Uesugi agreed to peace was due to exhaustion after nearly 30 years of war.

Despite the agreement, peace would not last in the Kanto. By the end of the 15th century, as with the region around Kyoto, the Kanto had fractured into rival territories controlled by numerous warlords. The Uesugi were initially in the strongest position, but by the time Shigeuji died in 1496, that was changing, and new powers were rising in the Kanto, but that’s a story for another time.

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The Kyotoku Rebellion