The Battle of Sekigahara

With the death of Toyotomi Hideyoshi, the Imjin War came to an end. However, peace did not follow. Soon, Japan plunged into internal conflict and division. The military faction and the civil faction clashed, and the Toyotomi family and the Tokugawa family were in opposition. Eventually, the entire country of Japan split into the Western and Eastern armies, and they collided at Sekigahara. The victor of this battle would become the ruler of Japan. It had been 1 year and 10 months since the end of the Imjin War.

 

 

1. The Tragedy of the Toyotomi Clan

Toyotomi Hideyoshi, who unified Japan during the Warring States period, had a son at the age of 53, named Tsuruatsu. However, Tsuruatsu was frail from birth and died after only two years. Hideyoshi was devastated by the loss, but he could no longer delay the decision of choosing a successor. He adopted his younger sister’s son, Hidetsugu, as his heir. In doing so, Hideyoshi appointed Hidetsugu to the position of Imperial Regent and himself took on the title of Taiko, which was even higher than that of the Regent. During this time, Hideyoshi had a biological son named Hideyori. With the birth of his own son, Hidetsugu’s position became precarious. Hidetsugu, who was an adopted nephew, now stood in the way of Hideyoshi’s biological son, Hideyori. Eventually, Hidetsugu was accused of treason for lending money to powerful lords, and Hideyoshi used this as a pretext to execute him. The purge was swift, and Hidetsugu’s family was annihilated. The powerful lords involved in the incident were also targeted for purge, but Tokugawa Ieyasu intervened and saved them. These lords later became strong supporters of Tokugawa Ieyasu. In 1598, Toyotomi Hideyoshi died, bringing an end to the Imjin War. His son, Hideyori, was only five years old.

 

2. The Conflict Between the Military and Civil Factions

Meanwhile, within the Toyotomi regime, there was a conflict between the military faction and the civil faction. The military faction had helped Toyotomi Hideyoshi militarily and participated in the Imjin War. On the other hand, the civil faction assisted him with administration, economy, logistics, and religion. Particularly, Ishida Mitsunari, who was Hideyoshi's closest aide, was a leader of the civil faction and known for his inflexibility and strong preferences, which made him unpopular with many military lords, including Kato Kiyomasa, who despised him. After Hideyoshi’s death, Tokugawa Ieyasu emerged as the most powerful figure in Japan. However, he could not immediately dominate the country. Hideyoshi had chosen five prominent lords, known as the "Gotairō ", to support his son, Hideyori, after his death. At the same time, the Five Regents acted as a check on Ieyasu. Among them, Maeda Toshiie was the second-most powerful figure in the Toyotomi regime and a close friend of Hideyoshi. Maeda Toshiie served as a guardian of the Toyotomi regime, keeping a close watch on Ieyasu, and acted as a mediator between the military and civil factions. In 1599, Maeda Toshiie died, and the conflict between the military and civil factions intensified. This led to an attack by the military faction, including Kato Kiyomasa, on Ishida Mitsunari. Mitsunari, who had been despised by many, turned to Tokugawa Ieyasu for help, and Ieyasu mediated a compromise. He also personally escorted Mitsunari to his safe haven in Sawayama Castle but simultaneously dismissed him from the " Gobugyō" position.

 

3. The Master of Patience

In the late 1580s, Tokugawa Ieyasu, though subservient to Toyotomi Hideyoshi, still held significant power. To weaken Ieyasu’s influence, Hideyoshi transferred Ieyasu’s domain to the Kanto region, which was at the time a remote area. However, Ieyasu transformed the Kanto region into a prosperous land, retaining influence over his former domain. As a result, he became one of Japan's most powerful lords. During the Imjin War, Ieyasu was frequently urged to send troops to Korea, but he refused, citing the need to manage the Kanto region and suppress rebellions. Thus, while other lords' military power weakened due to the war, Ieyasu preserved his strength. Even after Hideyoshi’s death, Ieyasu remained cautious. When Maeda Toshiie passed away, Ieyasu began to reveal his ambitions and began uniting his forces.

 

4. East-West Battle

Meanwhile, Ishida Mitsunari began rallying anti-Tokugawa forces to challenge Ieyasu. During this time, the Uesugi clan in Aizu began showing signs of rebellion against the central government, prompting Ieyasu to lead an army to suppress them. Seeing this as an opportunity, Ishida Mitsunari raised an army. Upon hearing that Ieyasu had changed course and was heading west, Mitsunari quickly gathered his forces and advanced toward Sekigahara. The armies met much sooner than anticipated, and the Battle of Sekigahara was fought on October 21, 1600, just 1 year and 10 months after the end of the Imjin War. Mitsunari's forces are referred to as the "Western Army," while Ieyasu’s forces are called the "Eastern Army." The Western Army consisted of 104,000 men, while the Eastern Army had 82,000. At the beginning of the battle, both armies fought fiercely. But around noon, Ieyasu targeted the forces of Kobayakawa Hideaki, a general in the Western Army, forcing him to switch sides. Ieyasu had been courting Kobayakawa even before the battle began. Midway through the battle, Kobayakawa defected to the Eastern Army, and this act of betrayal led to further defections among other lords. The tide of the battle quickly turned in favor of the Eastern Army, and soon the entire Western Army collapsed. After the battle, Ishida Mitsunari was captured and executed.

 

5. A Winning Army Wins Before the Battle

In reality, Ishida Mitsunari’s defeat was almost inevitable. The Western Army had already been struggling even before the battle began. Mitsunari’s lack of influence meant he could only gather troops by placing Mori Terumoto as a nominal general. The command structure was divided, and the "general" never appeared on the battlefield. Moreover, many of the Western Army’s lords were reluctant participants, and Mitsunari lacked the ability to control them. As a result, these lords did not support their allies during the battle and were passive or uncooperative. Eventually, they all defected. As Mencius said, "The advantage of timing is less than that of geography, and the advantage of geography is less than that of harmony." The Western Army’s situation epitomized this. In contrast, the Eastern Army, led by Tokugawa Ieyasu, was unified. While many of Hideyoshi’s retainers had joined both sides, those who joined the Eastern Army did so with the singular goal of removing Ishida Mitsunari. Additionally, Ieyasu frequently courted defections from the Western Army, and many lords wavered in their allegiance. As Sun Tzu said, "The winning army fights after winning, while the losing army seeks victory after fighting." Tokugawa Ieyasu had already won before the battle even began.

 

6. The Final Victor

Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu are collectively known as the "Three Heroes of the Warring States" in Japan. During the Warring States period, numerous warlords fought for supremacy, but in the end, Tokugawa Ieyasu emerged as the last victor. He patiently waited for the right moment to act, and although he made mistakes, he survived and carefully built his strength until the opportunity came. After Hideyoshi’s death, Ieyasu did not act rashly. When Maeda Toshiie passed away, Ieyasu seized the opportunity and demonstrated his abilities at the Battle of Sekigahara. After his victory, no one in Japan could oppose Tokugawa Ieyasu. He had truly become the most powerful man in Japan.