Prologue: The Rise and Death of Toyotomi Hideyoshi
Sengoku Jidai: A Brief introduction
For the past one hundred and thirty years, Japan has been in a perpetual state of civil war. The Ashikaga shoguns, once influential and powerful, had failed to command the respect of the minor lords, who began to fight and squabble against one another. One such lord, Oda Nobunaga, brought the the old order to it's knees at the Battles of Okehazama and Nagashino and in the year 1573, deposed the Ashikaga Shogunate. Nobunaga was well positioned to unite the land, however his retainer Akechi Mitsuhide had other ides, while his master was resting at Kyoto's Honno-ji Temple, Mitsuhide and his army surrounded the temple and set it alight. Nobunaga, his son Nobutada, wife Kicho and some of his best and most loyal retainers committed seppuku; their bodies perished in the flames.
Oda Nobunaga's grave: Koya mountain range, Kii province. Perhaps fittingly, Hideyoshi and Hideyori would also be buried at Mount Koya
Upon hearing word of Mitsuhide's betrayal, Nobunaga's surviving retainers lost no time in preparing to avenge their lord. His three most influential surviving retainers: Hashiba Hideyoshi (as he was then still known), Maeda Toshiie and Shibata Katsuie gathered their forces and closed in of Mitsuhide's position in Kyoto, Hideyoshi and Toshiie from the west, Katsuie from the east. Hideyoshi reached Mitsuhide first; their respective forces meeting at Yamazaki, eight days after Nobunaga's death at Honno-ji.
Hideyoshi: Rise to Power
Despite the rush to meet Mitsuhide (Hideyoshi's troops having march an average of forty kilometres a day in order to reach Kyoto before Katsuie or Toshiie did) Hideyoshi's army was battle hardened and more disciplined that Mitsuhide's, which consisted mostly of conscripts. Furthermore, Hideyoshi's army outnumbered Mitsuhide's by almost two to one, and was united in it's cause to avenge Nobunaga. Mitsuhide didn't stand much chance of a second Okehazama*, and worse, his men knew it.
The battle began well for Hideyoshi, who led a force to seize nearby Mt. Tenno and, using it as a vantage point, fired upon Mitsuhide's force below with their arquebuses. As mentioned earlier, much of Mitsuhide's army was conscripted, many would have never seen a drawn sword before, let alone an arquebus, and fled. Hideyoshi's main force charged in pursuit, and Mitsuhide was forced to fall back to his castle at Shoryuji. Fearing a fate not to dissimilar to that which he had inflicted on Nobunaga, Mitsuhide fled south alone before Hideyoshi's forces could surround the castle. His instinct proved correct and Hideyoshi did indeed surround Shoryuji, and some 250 of Mitsuhide's retainers committed seppuku rather than flee or surrender; each man braver than their master. Mitsuhide himself fled to the town of Ogurusu, where he was captured and killed by a glory-seeking peasant with a bamboo spear, a fitting end to the "Eight-day shogun"
Shoryuji Castle, as it stands today. The honourable actions of Mitsuhide's retainers saved it from the same fate which had befallen Honno-ji.
Having been the one to defeat Mitsuhide, Hideyoshi's position rose steadily amongst the remaining Oda retainers, who saw him as the best successor to Nobunaga. Fearing that Hideyoshi may supplant him as Nobunaga's successor, Oda Nobutaka, Nobunaga's third son, allied himself with Shibata Katsuie, who had taken Nobunaga's sister as his wife** and declared war on Hideyoshi's forces. Maeda Toshiie, although a good friend of Hideyoshi, was honour-bound to back Nobutaka. With the support of both Nobunaga's heir and sister, the Shibata faction had legitimacy on their side and most of the yet unaligned Oda retainers flocked to their banner. Hideyoshi was thus forced to rely on his own retainers, many of whom had little battle experience under the Oda. This time, Katsuie took the initiative, invading Hideyoshi's territory from the north, at Shizugatake.
As at Yamazaki, Hideyoshi's saviour at Shizugatake was his troops discipline and speed. Katsuie had not expected Hideyoshi's troops to arrive at Shizugatake for four days; they arrived within two. Initiative now belonged to Hideyoshi, whose troops smashed through Shibata's defences led by the great generals Fukushima Masanori and Kato Kiyomasa and aided by the strategies of Kuroda Kanbei. Shibata was forced back almost as quickly as he had pushed forward, and retreated to his castle in Echizen province. Not wanting to give Hideyoshi the satisfaction, he locked himself and his family in his castle and set it alight. Nobukatsu was captured alive and surrendered, committing seppuku shortly after (undoubtedly forced by Hideyoshi to do so). Maeda Toshiie was now free to back Hideyoshi as Nobunaga's successor, who "ascended to the Oda throne" unopposed, changing his name to Toyotomi Hideyoshi***. the Toyotomi clan was thus born.
Hideyoshi: Unification, Korea and Death
Hideyoshi still had one major obstacle in his quest to unite the Oda behind him, namely Nobunaga's second and only surviving son, Nobukatsu. Nobukatsu refused to submit to Hideyoshi, instead choosing to side with Nobunaga's oldest surviving ally, Tokugawa Ieyasu, the lord of Mikawa province. In 1584, two years after Nobunaga's death, Hideyoshi and Ieyasu gathered their forces and clashed in a series of battles known as the Komaki campaign. Both sides were well matched and the campaign ended in a stalemate, however Hideyoshi had more fiefs, more men and more money and thus greater capacity to wage war, and with this in mind, Ieyasu offered to submit to Hideyoshi along with Nobukatsu, his honour intact and fit to conquer the land another day. Hideyoshi accepted, and with Ieyasu and all remaining Oda fragments on his side, he was now easily the most powerful warlord in Japan.
Hideyoshi began unifying the rest of Japan in earnest, conquering the two islands of Shikoku and Kyushu within three years of the Komaki campaign. With Ieyasu's assistance, Hideyoshi was able to get Date Masamune, lord of Tohoku in northern Honshu, to submit without a fight. The last vestige of resistance to Toyotomi rule, the once mighty Hojo clan, fell in 1590.
With Japan consolidated, Hideyoshi fixed his gaze on Korea, the gateway to the riches of China. He launched two invasions of Korea during his lifetime, and rather like the Crusades, the first was highly successful, with Hideyoshi's forces managing to take the Seoul and Pyongyang and even push back the Koreans to Manchuria, yet also like the Christians during the First Crusade, Hideyoshi's forces could not sustain their momentum for long, and had to make do with a humiliating white peace.
In 1597, only a year before his death, Hideyoshi commissioned a second invasion of Korea. This time the Koreans were ready for the Japanese, who were largely confined to the southern tip of the Korean peninsula. Much of the blame for the disastrous second campaign belongs to the Grand Commander, 15 year old neophyte Kobayakawa Hideaki, appointed by Hideyoshi based on his father's (Kobayakawa Takakage) rather than his own reputation. Despite being aided by Kuroda Kanbei, arguably Hideyoshi's best strategist, Hideaki's incompetence cost the Japanese dearly during the early stages of the campaign, and on the advice of a then unknown bureaucrat and Toyotomi advisor, Ishida Mitsunari, was replaced by Kato Kiyomasa (hero of Shizugatake and the first Korean campaign) and Konishi Yukinaga (another hero of the First Korean Campaign).
Although Mitsunari was undoubtedly right to dismiss the incompetent Kobayakawa Hideaki, Kuroda Kanbei (shown above) took this as a personal slight against himself by Mitsunari and never forgave him for it. It was neither the first nor last time that Mitsunari's direct manner made him an enemy for life.
Kiyomasa and Yukinaga were bitter rivals and hated each other tenfold more than they hated the Koreans but nevertheless they knew the enemy well and proved an effective team. The Japanese forces' fortunes began to improve, managing to besiege Ulsan by 1598, however urgent news soon reached Ulsan from Kyoto. Hideyoshi had called the invasion off and summoned his retainers to his castle in Osaka; he was gravely ill and dying...
* Referring to the Battle of Okehazama, where Oda Nobunaga defeated a professional army of around 30'000 men with just under 3'000.
** Her first husband being Nobunaga's late rival, Asai Nagamasa.
*** Up until the 20th Century, it was not uncommon for Japanese (or Chinese, or Korean for that matter) men to take several names during their lifetime. Before taking the name Hashiba Hideyoshi, Hideyoshi had been previously known as Kinoshita Tokichiro. In real history, Hideyoshi didn't change his name to Toyotomi until after the Komaki Campaign.