Ieyasu and Hideyoshi
In 1584, Ieyasu decided to support Oda Nobukatsu, the eldest son and heir of Oda Nobunaga, against Hideyoshi. This was a dangerous act and could have resulted in the annihilation of the Tokugawa.
Tokugawa troops took the traditional Oda stronghold of Owari, Hideyoshi responded by sending an army into Owari. The Komaki Campaign was the only time any of the great unifiers of Japan fought each other: Hideyoshi vs. Ieyasu. The campaign proved indecisive and after months of fruitless marches and feints, Hideyoshi settled the war through negotiation. First he made peace with Oda Nobukatsu, and then he offered a truce to Ieyasu. The deal was made at the end of the year; as part of the terms Ieyasu's second son, O Gi Maru, became an adopted son of Hideyoshi.
Ieyasu's aide, Ishikawa Kazumasa, chose to join the pre-eminent daimyo and so he moved to Osaka to be with Hideyoshi. However, only a few other Tokugawa retainers followed this example.
Hideyoshi was understandably distrustful of Ieyasu, and five years passed before they fought as allies. The Tokugawa did not participate in Hideyoshi's successful invasions of Shikoku and Kyűshű.
In 1590 Hideyoshi attacked the last independent daimyo in Japan, H˘j˘ Ujimasa. The Hojo clan ruled the eight provinces of the Kant˘ region in eastern Japan. Hideyoshi ordered them to submit to his authority and they refused. Ieyasu, though a friend and occasional ally of Ujimasa, joined his large force of 30,000 samurai with Hideyoshi's enormous army of some 160,000. Hideyoshi attacked several castles on the borders of the H˘j˘ clan with most of his army laying siege to the castle at Odawara. Hideyoshi's army captured Odawara after six months (oddly for the time period, deaths on both sides were few). During this siege, Hideyoshi offered Ieyasu a radical deal. He offered Ieyasu the eight Kant˘ provinces which they were about to take from the H˘j˘ in return for the five provinces that Ieyasu currently controlled (including Ieyasu's home province of Mikawa). Ieyasu accepted this proposal. Bowing to the overwhelming power of the Toyotomi army, the H˘j˘ accepted defeat, the top H˘j˘ leaders killed themselves and Ieyasu marched in and took control of their provinces, so ending the clan's reign of over 100 years.
Ieyasu now gave up control of his five provinces (Mikawa, T˘t˘mi, Suruga, Shinano, and Kai) and moved all his soldiers and vassals to the Kant˘ region. He himself occupied the castle town of Edo in Kant˘. This was possibly the riskiest move Ieyasu ever made Ś to leave his home province and rely on the uncertain loyalty of the formerly H˘j˘ samurai in Kant˘. In the event, it worked out brilliantly for Ieyasu. He reformed the Kant˘ provinces, controlled and pacified the H˘j˘ samurai and improved the underlying economic infrastructure of the lands. Also, because Kant˘ was somewhat isolated from the rest of Japan, Ieyasu was able to maintain a unique level of autonomy from Hideyoshi's rule. Within a few years, Ieyasu had become the second most powerful daimyo in Japan. There is a Japanese proverb which likely refers to this event: "Ieyasu won the Empire by retreating."
In 1592, Hideyoshi invaded Korea as a prelude to his plan to attack China (see Japanese invasions of Korea [1592ľ1598] for more information about this campaign). The Tokugawa samurai never took part in this campaign. Early in 1593, Ieyasu was summoned to Hideyoshi's court in Nagoya (in Kyűshű, different from the similarly spelled city in Owari Province), as a military advisor. He stayed there, off and on for the next five years. Despite his frequent absences, Ieyasu's sons, loyal retainers and vassals were able to control and improve Edo and the other new Tokugawa lands.
In 1593, Hideyoshi fathered a son and heir, Toyotomi Hideyori.
In 1598, with his health clearly failing, Hideyoshi called a meeting that would determine the Council of Five Elders, who would be responsible for ruling on behalf of his son after his death. The five that were chosen as regents (tair˘) for Hideyori were Maeda Toshiie, M˘ri Terumoto, Ukita Hideie, Uesugi Kagekatsu, and Ieyasu himself, who was the most powerful of the five. This change in the pre-Sekigahara power structure became pivotal as Ieyasu turned his attention towards Kansai; and at the same time, other ambitious (albeit ultimately unrealized) plans, such as the Tokugawa initiative establishing official relations with Mexico and New Spain, continued to unfold and advance.
Hideyoshi, after three more months of increasing sickness, died on September 18, 1598. He was nominally succeeded by his young son Hideyori but as he was just five years old, real power was in the hands of the regents. Over the next two years Ieyasu made alliances with various daimyo, especially those who had no love for Hideyoshi. Happily for Ieyasu, the oldest and most respected of the regents died after just one year. With the death of Regent Maeda Toshiie in 1599, Ieyasu led an army to Fushimi and took over Osaka Castle, the residence of Hideyori. This angered the three remaining regents and plans were made on all sides for war. It was also the last battle of one of the most loyal and powerful retainer of Ieyasu, Tadakatsu Honda .
Opposition to Ieyasu centered around Ishida Mitsunari, a powerful daimyo but not one of the regents. Mitsunari plotted Ieyasu's death and news of this plot reached some of Ieyasu's generals. They attempted to kill Mitsunari but he fled and gained protection from none other than Ieyasu himself. It is not clear why Ieyasu protected a powerful enemy from his own men but Ieyasu was a master strategist and he may have concluded that he would be better off with Mitsunari leading the enemy army rather than one of the regents, who would have more legitimacy.
Nearly all of Japan's daimyo and samurai now split into two factionsŚMitsunari's group and the anti-Mitsunari Group. Ieyasu supported the anti-Mitsunari Group, and formed them as his potential allies. Ieyasu's allies were the Date clan, the Mogami clan, the Satake clan and the Maeda clan. Mitsunari allied himself with the three other regents: Ukita Hideie, Mori Terumoto, and Uesugi Kagekatsu as well as many daimyo from the eastern end of Honshű.
In June 1600, Ieyasu and his allies moved their armies to defeat the Uesugi clan who was accused of planning to revolt against Toyotomi administration (Led by Ieyasu, top of Council of Five Elders). Before arriving to Uesugi's territory, Ieyasu had got information that Mitsunari and his allies moved their army against Ieyasu. Ieyasu held a meeting with daimyo, and they agreed to ally with Ieyasu. He then led the majority of his army west towards Kyoto. In late summer, Ishida's forces captured Fushimi.
Ieyasu and his allies marched along the T˘kaid˘, while his son Hidetada went along the Nakasend˘ with 38,000 soldiers. A battle against Sanada Masayuki in Shinano Province delayed Hidetada's forces, and they did not arrive in time for the main battle.
Battle of Sekigahara
This battle was the biggest and likely the most important battle in Japanese history. It began on October 21, 1600 with a total of 160,000 men facing each other. The Battle of Sekigahara ended with a complete Tokugawa victory. The Western bloc was crushed and over the next few days Ishida Mitsunari and many other western nobles were captured and killed. Tokugawa Ieyasu was now the de facto ruler of Japan.
Immediately after the victory at Sekigahara, Ieyasu redistributed land to the vassals who had served him. Ieyasu left some western daimyo un-harmed, such as the Shimazu clan, but others were completely destroyed. Toyotomi Hideyori (the son of Hideyoshi) lost most of his territory which were under management of western daimyo, and he was degraded to an ordinary daimyo, not a ruler of Japan. In later years the vassals who had pledged allegiance to Ieyasu before Sekigahara became known as the fudai daimyo, while those who pledged allegiance to him after the battle (in other words, after his power was unquestioned) were known as tozama daimyo. Tozama daimyo were considered inferior to fudai daimyo.
Shogun Ieyasu (1603ľ1605)
On March 24, 1603, Tokugawa Ieyasu received the title of shogun from Emperor Go-Y˘zei. Ieyasu was 60 years old. He had outlasted all the other great men of his times: Nobunaga, Hideyoshi, Shingen, Kenshin. He was the shogun and he used his remaining years to create and solidify the Tokugawa shogunate (That was eventually to become the Edo period, about two hundred years under Ieyasu's Shogunate), the third shogunal government (after the Minamoto and the Ashikaga). He claimed descent from the Minamoto clan by way of the Nitta family. Ironically, Ieyasu's descendants would marry into the Taira clan and Fujiwara Clans. The Tokugawa Shogunate would rule Japan for the next 250 years.
Following a well established Japanese pattern, Ieyasu abdicated his official position as shogun in 1605. His successor was his son and heir, Tokugawa Hidetada. This may have been done, in part to avoid being tied up in ceremonial duties, and in part to make it harder for his enemies to attack the real power center, and in part to secure a smoother succession of his son. The abdication of Ieyasu had no effect on the practical extent of his powers or his rule; but Hidetada nevertheless assumed a role as formal head of the bakufu bureaucracy.