The Sengoku Jidai is also known as the “Warring States Period” to English scholars, which is actually an almost literal translation.(1) While English Japanese historians can agree on the name of the era, for some reason, they cannot agree on the years. Many start the beginning of the Sengoku Jidai with the Ōnin War (1467-1477). Some start it with the birth of Oda Nobunaga in 1534. Starting there, however, skips over a large part of history that should be considered part of the Sengoku Jidai, for the country was thrown into civil war long before then. When it actually ends has also not been agreed upon by historians. There are three distinct events that historians label as the end of the Sengoku Jidai: the Siege of Odawara Castle in 1590, the Battle of Sekigahara in 1600, and the Summer Siege of Ōsaka Castle in 1615. To make sure nothing is left out, The Sengoku Archives will cover the years of 1467 to 1615.(2)
The Ōnin War (1467-1477)
The Ōnin War is seen as the catalyst for the Sengoku Jidai. The war broke out over a succession dispute within the Ashikaga Shogunate. The shōgun at that time, Ashikaga Yoshimasa, wanted to retire from the office, but he had no heir to take over for him. In 1464, Yoshimasa began trying to persuade his brother, Ashikaga Yoshimi, to leave his life as a monk and become the new shōgun. Things become complicated when Yoshimasa’s wife, Tomiko, gave birth to a son named Yoshihisa. The issue of succession was brought to the attention of Hosokawa Katsumoto and Yamana Sōzen, both leaders of clans who worked under the shōgun. They stood on opposing sides on who should take over as the new shōgun: Hosokawa sided with Yoshimasa and Yoshimi, while Yamana sided with Tomiko and the newborn, Yoshihisa. Tensions began to rise and eventually led to the Hosokawa and Yamana clans fighting within the city of Kyōto in 1467, thus beginning the Ōnin War. The war ended with no clear victors. Both Hosokawa Katsumoto and Yamana Sōzen both died in 1473, just four years before the end of the war. By 1477, the city of Kyōto laid in ruins. The Ashikaga Shogunate lost considerable power after the war, serving as puppets to the Hosokawa who managed to gain control of the shogunate in 1490.(3) The divide that the Ōnin War caused spread outside of Kyōto, which resulted in the Sengoku Jidai.
“Gekokujō”, loosely translated to “the low oppress the high”, is a phenomenon that came about in the aftermath of the Ōnin War. George Sansom in A History of Japan 1334-1615 explains the ways how this phenomenon manifested:
“[…] (a) in the emancipation of a number of agricultural workers, who became independent farmers on a small scale; (b) in the rise of an influential class of traders and moneylenders; (c) in the growing strength of independent local warriors (ji-samurai), who formed associations to resist the depredations of Constables and other rural magnates; and (d) in the seizure of power in both national and provincial government by former vassals or retainers of the leading warrior houses.”(4)
Clans that were once prominent ages ago collapsed with the rise of others. Great examples of this gekokujō phenomenon are Mōri Motonari (1497-1571), who overthrew the Ōuchi clan and gained control of the Chūgoku region, and Saitō Dōsan (1494-1556), who was a monk turned oil merchant turned daimyō of Mino. Other figures that were active during this era were Takeda Shingen, Uesugi Kenshin, Hōjō Ujiyasu, and Imagawa Yoshimoto.
Also during this era, we see the rise of the Ikkō-ikki, Buddhist warrior monks who managed to gain control of the province of Kaga after a revolt in 1488.(5) These warriors will be covered in an article all their own, but just know that their rise to power during this time will put them in direct conflict with Oda Nobunaga later on.
On top of this, Portuguese first land on Japanese shores in 1543, bringing with them a new culture along with new technology (guns) and a new religion (Christianity). Their arrival in Japan would change the course of Japanese history, for a lot of battles could have turned out differently if not for their technologies, and despite constantly being banished from the country, the missionaries did manage to establish a Christian presence in Japan, even though they never got to see the fruits of their labor.
The Three Unifiers (1560-1615)
The Three Unifiers really played a part for only the last fifty-five years of the Sengoku Jidai. These men were Oda Nobunaga, Toyotomi Hideyoshi, and Tokugawa Ieyasu. These men were quite different from one another, which can be seen in a poem that Japanese schoolchildren have to learn.(5) The Three Unifiers were asked what they would do to a bird that would not sing. Nobunaga said that he would kill it, Hideyoshi said that he would make it sing, and Ieyasu said that he would wait for it to sing. These would be the men who would lay the foundations for reunification.
Age of Oda Nobunaga (1560-1582)
The first Unifier was Oda Nobunaga (1534-1582). He made his first move towards the reunification of Japan in 1560 at the Battle of Okehazama. From there, he began to expand his territory and helped restore and destroy the Ashikaga Shogunate. He changed the dynamics of Japanese warfare at the Battle of Nagashino in 1575. Nobunaga was close to conquering Japan, however, he perished at Honnōji when one of his retainers, Akechi Mitsuhide (1528-1582), turned traitor and had his army attack the so called “Demon King” as he rested at the temple in Kyōto in the early morning hours of June 21, 1582.
Age of Toyotomi Hideyoshi (1582-1598)
Toyotomi Hideyoshi (1537-1598) was the next Unifier to try to take over Japan. He would avenge Nobunaga’s death by killing Akechi Mitsuhide at the Battle of Yamazaki. He would wind up taking over the remaining Oda land and through many campaigns he managed to conquer Japan after the Siege of Odawara Castle in 1590. Hideyoshi was actually the one to reunify the country, but he did not take the title of shōgun (mainly because of his peasantry background). Instead, he took the title of kampaku, which was similar to the role of prime minister. Despite this title, Hideyoshi still ran the country like he held the title of shōgun. He made major changes to Japanese military and social classes, and even tried to extend his reach beyond the shores of Japan by trying to conquer China via Korea. This resulted in two separate Korean Campaigns, one in 1592 and the other in 1597.
Age of Tokugawa Ieyasu (1598-1616)
Toyotomi Hideyoshi passed away in September 1598, leaving behind his five-year-old son, Hideyori (1593-1615?), and a group of generals and administrators to run the country. Problems arose when the third Unifier, Tokugawa Ieyasu (1543-1616), began taking the steps to completely take over the Toyotomi regime. Ishida Mitsunari (1559-1600), a man loyal to the Toyotomi, made attempts to stop Ieyasu. This caused a divide within the Toyotomi clan: the Western army under Mitsunari and the Eastern Army under Ieyasu. After a year of small skirmishes between the two sides, they would finally meet at Sekigahara on October 21, 1600. Ieyasu defeated Mitsunari and went on to become shōgun in 1603.
Tokugawa Ieyasu stepped down as shōgun in 1605, allowing his son, Tokugawa Hidetada (1581-1632), to take his place. The Tokugawa Period, also known as the Edo Period (1603-1868), was underway. There was still a problem, for Toyotomi Hideyori was gathering support from many rōnin across the country who came to stay at his father’s castle at Ōsaka. This posed a threat to the newly established shogunate, so Ieyasu took to the battlefield one last time and laid siege to Ōsaka Castle in the winter of 1614. After a small time of peace, Ieyasu laid siege to the castle again in the summer of 1615, which ended with the castle in flames and Hideyori dead. The Sengoku Jidai had finally come to an end. Ieyasu would pass away the next year, managing to live through a lifetime of war.
- 戦国時代 = “Warring States Period” (Google Translate)
- This seems to be the timeline most historians are going with nowadays. However, some break down the era much more than I have in the article, referring to the era before the Three Unifiers as the Sengoku Jidai, while the era of the Three Unifiers is sometimes referred to as the Azuchi-Motoyama Period.
- Samson, George. A History of Japan 1334-1615 (1961). p. 233
- Samson, George. A History of Japan 1334-1615 (1961). p. 235
- Turnbull, Stephen. Japanese Warrior Monks AD 949-1603 (2003). p. 15
- Chaplin, Danny. Sengoku Jidai Nobunaga, Hideyoshi, and Ieyasu: Three Unifiers of Japan (2018). p. ix