How did Oda Nobunaga Unify Japan?

Powerful Samurai to Push Forward to End a Turbulent Era, but Assassinated

A genius warlord, Oda Nobunaga (1534-1582, 織田信長), pushed forward to end a turbulent era. There are several factors in Nobunaga's success, such as his overwhelming military, strategic, and economic power. But his rational thinking was the driving force behind bringing an end to the warfare that had continued for over 100 years. He was close to unifying Japan after a tremendous number of battles throughout his life, but was killed at the Honnoji incident by his retainer, Akechi Mitsuhide, in 1582.

Nobunaga was born at Shobata Castle in the Owari Province (present-day western Aichi Prefecture), near Tsushima and Atsuta ports, the junction of the Ise Bay Sea Route, and the three large rivers (Kiso, Nagara, and Ibi). By controlling Tshushima Port, Nobunaga amassed enormous revenues from taxes and customs duties. Recognizing the importance of the economy, Nobunaga later expanded his control of the port to include Mikuni Port, which was controlled by the Asakura clan in Echizen (present-day Fukui Prefecture), and Lake Biwa on the way to Kyoto, to gain control of Japan's sea route. He was called the "Great Fool" in his youth because his behavior was unconventional. However, these experiences bore their future fruits. At the age of 27, Nobunaga prepared carefully and logically and succeeded in defeating the supreme lord of the Suruga province (present-day Shizuoka Prefecture), nicknamed "the best archer", Imagawa Yoshimoto’s large army of more than 25,000 warriors with only 2,000 of his elite troops, including Meda Toshiie, the head of Red Horo Shu, and Sassa Masanari, the head of Black Horo Shu, at the Battle of Okehazama. Nobunaga quickly emerged in the Samurai world of the Warring States Period (1467-1590).

Seven years later, once he defeated the Saito clan in Mino (present-day Gifu prefecture) and entered Gifu Castle, he started to use his stamp under the slogan of Tenka Fubu (天下布武), meaning bringing the peace to the realm through the military power in his letters to advocate for the pacification and unification in Gokinai  (five provinces including Kyoto and surroundings) despite the presence of more powerful military lords. In addition, Nobunaga began to use a Kao (written seal mark) that featured the character "麟" from "Kirin, 麒麟," an imaginary creature symbolizing a peaceful world. This change occurred after Ashikaga Yoshiteru, the 13th shogun of the Muromachi shogunate, was killed by his retainers and warlords such as the Miyoshi clan, marking the definitive fall of the shogunate.

Nobunaga entered Kyoto under the leadership of Ashikaga Yoshiaki, Yoshiteru's brother, and supported him to become the 15th shogun. After that, Nobunaga defeated his opponents one after another, expanding his territory from Owari (Tokai) and Kinai (Kyoto and Osaka) to Hokuriku, and others. During his invasion of Echizen Asakura territory, Nobunaga confronted the biggest crisis in his life near Kanegasaki Castle, with the Asakura army charging forward in front and the Azai army attacking from behind. Nobunaga was about to be crushed by both, but successfully retreated to Kyoto, then to his Gifu Castle. After that, he defeated both the Asakura and the Azai clans.

In parallel, Osaka Hongwanji, the head temple of the Jodo Shinshu Buddhism sect, stood in front of Nobunaga. The battles against the Honganji continued for around 10 years. In 1575, Nobunaga and Tokugawa Ieyasu (1543-1616, 徳川家康) forces attacked and defeated the brave and strong cavalry of the Takeda clan with relentless gunfire at the Battle of Nagashino and Shitaragahara. But the Takeda clan retained and grew its power. In 1580, Nobunaga finally made a peace agreement with the Osaka Honganji Temple at the order of Emperor Ogimachi and received the temple land, located on the edge of the Uemachi Plateau facing Osaka Bay, as an important traffic point to the west and abroad. Nobunaga was so happy and held Japan's first illumination festival at Azuchi Castle. Seeing Azuchi Castle floating in the darkness, many people must have felt a sense of realizing the peaceful world.

Nobunaga appointed an innovator, Sen-no-Rikyu (1522-1591, 千利休), as his tea master to conduct tea ceremonies mainly at Myokakuji Temple in Kyoto, showing the Ashikaga shogun's tea utensils to his retainers as a symbol of samurai authority and firm unity for future battles.

In 1582, Nobunaga received an opportunity to defeat the Takeda clan. Immediately, he invaded and defeated the Takeda clan. However, 83 days later, Nobunaga was unexpectedly killed by his vassal, Akechi Mitsuhide, at Honnoji Temple. He fulfilled his task as an outstanding Samurai to the end. That is, his head did not fall into Mitsuhide’s hands. Therefore, the rumor, "Nobunaga is alive," spread and circulated among many Samurai, causing many Samurai not to join Mitsuhide. Consequently, Mitsuhide was struck down by Nobunaga’s other right hand, Toyotomi Hideyoshi (1537-1598, 豊臣秀吉), at the Battle of Yamazaki in southern Kyoto.

“The 50 years of the human world, one of the 6 realms of Buddhism, is fleeting and short, so let us live to the fullest without fear of death.”

This is a verse from Atsumori that Nobunaga chanted and danced before heading off to the Battle of Okehazama at the age of 26 and before committing suicide at the Honnoji Temple at the age of 49.

Nobunaga aimed to end the Warring States period with military power under the slogan of Tenka Fubu. He was, after all, a genius who emerged in the age of turmoil. Warlords of the Warring States period strove to expand their territory, and Nobunaga was the first to offer a vision of Japan as a nation.

Oda Nobunaga Map

Notable sites

Oda Nobunaga Timeline

1336	Ashikaga Takauji estabilished Muromachi Shogunate	Muromachi Period	-
1467	Onin War started (- 1477)		-
1493	Hojo Soun - the first warlord in Japan history - settled Izu province by defeating Horikoshi Kubo		-
1534	Nobunaga was born in Owari province		Age=1
1552	Nobunaga inherits leadership of the Oda family		19
1560	Nobunaga defeated Imagawa Yoshimoto at the battle of Okehazama		27
1563	Nobunaga built his 1st own Komakiyama Castle		30
1567	Nobunaga moved to Gifu Casle and started to use the "Tenka-fubu" stamp		34
1568	Nobunaga went up Kyoto bringing Ashikaga Yoshiaki		35
1570	Osaka Hongwanji raised the army against Nobunaga		37
1571	Nobunaga defeated Enryakuji Temple's monk solduers		38
1573	Nobunaga defeated the Azai and Asakura clans and ousted Ashikaga Shogun from Kyoto		40
1575	Nobunaga won against Takeda Clan at the battle of Nagashino	Azuchi Momoyama Period	42
1576	Nobunaga started the constraction of Azuchi Castle		43
1579	The Azuchi Castle Tower was completed		46
1580	Nobunaga made peace with Ishiyama Hongwanji Temple		47
1582	Nobunaga and Tokugawa defeated the Takeda clan		49
1582	Nobunaga was killed at Honnoji by Akechi Mitsuhide		49
1582	Hideyoshi defeated Akechi Mitsuhide		-
1590	Hideyoshi unified the nation		-
1598	Hideyoshi passed away		-
1600	Tokugawa Ieyasu defeated Ishida Mitsunari, Hideyoshi's right arm at the battle of Sekigahara		-
1603	Ieyasu estabished Tokugawa Shogunate at Edo	Edo Period	-
1615	Toyotomi's Osaka Castle burnt down at the Siege of Osaka (Toyotomi clan ended)		-