Invasion of Iga
The Great Campaign Against Iga
Oda Nobunaga was otherwise busy for the next two years before he could deal with the problem in Iga. When two Samurai, Fukuchi Iyo from a village above Tsuges in Iga, and his comrade Mimisu Iyajiro, offered him their services as advisors and guides, Nobunaga saw his chance to finally subjugate Iga because they did not accept his supremacy. Oda Nobunaga planned a far larger operation than his son Oda Nobuo did when he failed in 1579.
Oda Nobunaga planned to attack from six sides simultaneously, with Fukuchi Iyo and Mimisu Iyajiro advancing through Kōga Province from the north, as that route was the most difficult to defend.
Oda Nobunaga himself led the forces that left Azuchi in August 1581, but after only half a day’s march he fell ill and had to call off the operation. By September his health was restored and he summoned his generals. His plan was to burn and devastate as much as possible to prevent the tactics of the people of Iga.
The people of Iga found out about the six armies in good time, but they did not have the resources to defeat such a large force.
The troops in Iga were about 4,000 soldiers, so they decided to concentrate their forces in two places and defend from there. One was the Heirakuji Temple on a small hill in Ueno Village, the site where Iga Ueno Castle now stands. The other place was Mount Tendoyama, not far from where Maruyama Castle once stood. Nobunaga’s troops used six different routes:
The route via Iseji was commanded by Oda Nobuo or Kitabatake Chujo Nobuo as he was also known. At his side rode Yoshida Goro and Oda Shichibei no Jo Nobuzuma along with more than 10,000 soldiers and mounted Samurai. He was also joined by all those who had already taken part in the 1579 invasion, alongside other Takigawa Saburohei Kazumasu, Nagano Sakyo, and Hioki Daizenryo, but this time together in one army. After a quick push, Nobuo split his army into three to attack the villages and forts where refugees from Iga were staying. Takigawa besieged two fortresses, Tanenama no Sho and Kunimiyama, while Nagano and Hioki attacked the Valley of Ao and the fortress at Kashiwao. He did not meet much resistance during his campaign, but they were often harassed by the besieged. During the nights they launched attacks on the besiegers.
More than 12,000 soldiers came through the Kōga area from the north. They moved past Tsuge near the borders further south. The army was led by Niwa Gorozaemon Nagashida, Takigawa Sakon Shogen, Takigawa Yoshidaou, Wakabe Sakyo no Shinjuko, and Todo Shogen. Niwa Nagashida’s camp was attacked by Ninja at every opportunity, so that in the end no one dared to sleep for fear of being killed.
Over 7,000 soldiers also came through the Kōga area from the north, but chose the western route through the village of Tamataki. The army was commanded by Gamo Hida no Kami Shikyo, Wakizaka Jinnai Yasuharu and Yamaoka Shukei Gashira, which is not a name but means purser. The army is said to have encountered resistance on its way through Kōga. Apparently, it was a member of the Mochizuke family named Mochizuke Chotaro who had a duel with a man named Yamauchi Zaemon Dono. One reason for this may have been the alliance of the Iga and Kōga families.
From the northwest came Hori Kudaro Hidemasa and Tarao Shirobei Mitsuhiro with 2,300 men. The people of the northwest region of Iga decided to defend Kannoji, a Buddhist temple on Mount Hijiyama west of Ueno.
Masanoiyabei Nagamasa, Shinjo Suruga no Kami, Ikoma Gagaku Kashira, Mori Iki no Kami, Toda Danzo Shoshitsu, Sawabara Jiro, Akiyama Sanou Tayu and Yoshino no Miya Naishoyu attacked from Yamato province in the south with 10,000 troops. They besieged Kashiwabara, which was under the supreme command of Takano, a Samurai who was an expert at night raids. He used ancient methods, those of Kusunoki Masashige, the founder of Kusunoki-Ryū. One technique he used was to have women and children wave torches, giving the impression of an impending attack and spreading fear and disorder in enemy camps.
Tsutsui Junke and his nephew Tsutsui Shiro Sadatsugu also attacked from Yamato to the south, but via the town of Kasama further north than Asano Nagamasa’s army. The army consisted of 3,000 soldiers, but they moved north to help Gamo Ujisato in besieging Hijiyama instead of besieging Kashiwabara.
On September 27, Gamo Ujisato, Wakizaka Yamaoka, and Tsutsui Hijiyama attacked together, but small groups of Ninja were hiding along the embankment. It was the same strategy that had been used successfully in Nobuo’s invasion. They attacked Gamo on his way up, inflicting so much damage that Gamo’s troops were badly wounded and lacked fighting spirit by the time they reached the mountaintop.
Guerrilla Tactics Against the Attackers
Two men from Iga, Momoda Tobei and Yokoyama Jinsuke managed to reach the foot of the mountain and take the heads of Gamo’s two sons. The besiegers immediately broke off their attack and retreated. Momoda Tobei, Fukukita Shogen, Mori Shirozaemon, Machii Kiyobei, Yokoyama Jinsuke, Yamada Kanshiro and another man who was called the Seven Spears were reaped great honors for their success in battle.
Iga’s forces decided to continue their night raids against the enemy. They prepared a swift attack on Tsutsui’s army, surprising him. His soldiers didn’t even have time to put on their armor, and a wind blew out all the torches. Because of the darkness, Tsutsui’s soldiers slaughtered each other. The troops of Iga, on the other hand, used code words to know who was enemy or friend. Another attack on Tsutsui’s army was also successful.
The Defeat of the Insurgents
After successfully repelling all resistance, Oda Nobunaga’s armies rallied around Hijiyama. 30,000 soldiers from his once 44,300 strong army surrounded the mountain. Due to the huge advantage, Oda Nobunaga failed to win the fight by force of arms. Because the weather was dry and the wind was strong, Oda Nobunaga decided to set fire to the entire area. Those who tried to escape from the flames were driven back.
This was the end of the last major uprising in Iga and those who continued to fight Oda spread throughout the region. Whether the fall of Hijiyama took place on September 10 or 11, 1581, or as late as early October is unclear. The Nobunaga’s forces began their hunt for the last resisters, and it was not until 1582 that all resistance was defeated.
The Survivors Are Hiding
Few of Iga’s once 4,000-strong army remained, and many innocents lost their lives in Nobunaga’s furious pursuit of Ninja. Although most knew about the Ninja, only a minority belonged to the clans or were trained in the art of Ninjutsu. Some sources report that only eight survivors from the three Hattori clans remain. Many fled to other areas of Japan. A jōnin of the Hattori family was killed in Tsutsui’s attack on Kikyo Castle.
A final attempt to assassinate Nobunaga was made by Kido, Harada, and Jindai. The whole thing took place when Oda Nobunaga was traveling through Iga to observe the successes of his invasion. Oda Nobunaga reached a place called Ichinomya. Kido, Harada and Jindai had set up three cannons from three different directions. They opened fire on the place where Nobunaga and his followers were sitting, but Nobunaga managed to survive, but seven or eight of his followers perished. Kido, Harada and Jindai managed to escape into the woods.
Momochi Sandayu, a well-known jōnin, also managed to escape from Nobunaga’s troops with some of his men. They fled to the town of Ryugu near Ude Sanbonmatsu in Yamato Province, where Momochi and his men stayed until June 10, 1582, although his men wanted to continue fighting. On June 10, word reached them that Oda Nobunaga had been assassinated by his own general, Akechi Mitsuhide.