Tenshō Iga wars (1579- 1581)
Precious few detailed contemporary accounts can be found on ninjutsu, but a few documented events do exist, of which the most well-known is the conquering and destruction of the Iga province. It put an end to Iga Sokoku Ikki (伊賀惣国一揆) which was maintained by independent ninja families to form a system of governance in Iga, and forced the iga no mono ninja families into exile to escape the genocide in Iga.
Known as the unifier of Japan, Oda Nobunaga had forced Kitabatake Tomofusa, the defeated ruler of Ise, to adopt his son Oda Nobukatsu. Soon after this, Nobukatsu seized power in Ise for himself and the young man – now ruler of Ise – decided to expand his dominion by conquering Iga. Nobukatsu sent Takigawa Kazumasu to build a fortress in Maruyama, Iga, which would function as a base for the war campaign.
The iga no mono (ninja) soldiers noticed the construction of the fortress and attacked it while it was still incomplete. They attacked Maruyama at midday on 24th November 1578. Takigawa was caught by surprise and had to retreat with his forces as the Iga troops put the fortress to the torch. He succeeded in gathering his remaining forces in nearby Tsuzumigamine, where they suffered yet another defeat and beat a tactical retreat once more back to Ise.
Angry and humiliated, Nobukatsu set his sights on an immediate onslaught against Iga, but his counsel advised patience. A year later, Nobukatsu began his attack, planning a three-pronged assault and leaving Matsugashima on 6th October 1579. The Iga forces, however, caught wind of Nobukatsu’s machinations and prepaired their own counterstrike. Nobukatsu with his main force of 8,000 men arrived in Iga through Nagano mountain pass on the following day, and there the men of Iga ambushed them. The Iga side exploited the mountainous landscape and guerilla tactics to surprise and bewilder Nobukatsu’s army. Once again, he retreated, this time under heavy losses. Two additional smaller army bands – Tsuge Saburō leading 1,500 men through the Onikobu pass, and Nagano Sakyōnosuke leading 1,300 men through the Aoyama pass – met the same fate. Tsuge lost his life. According to the literary history of Iga, the Iranki, Nobukatsu’s losses numbered in the thousands.
The campaign was an unmitigated catastrophe. Nobukatsu was thwarted and suffered the loss of one of his generals. Moreover, Nobukatsu neglected to inform his father of his plans before they began. Nobukatsu had wished to prove his worth to his father by conquering Iga, but instead Nobunaga was incensed upon hearing of his son’s deeds and scolded him.
The Second Tenshō Igan War (30th September – 8. October 1581)
On 30th September 1581, Nobunaga set his own attack on Iga in motion, his on a much grander scale than his son’s. At this time, Oda was at the peak of his power, governing the greater part of central Japan including all the provinces surrounding Iga. He was therefore able to assemble a great army which laid struck Iga from six different directions.
Oda Nobunaga divided his army as follows:
1. 12,000 men led by Niwa Nagahide and Takigawa Kazumasu arriving from the northeast.
2. 10,000 men commanded by Nobukatsu and Tsuda Nobusumi arriving from Ise via Aoyama pass from the southeast.
3. 7,000 men under Gamō Ujisato ja Wakisaka Yasuharu to arrive from Tamataki in the north.
4. 7,000 men led by Asano Nagamasa arriving from Hase in the southwest.
5. 3,700 men led by Tsutsui Junkei arriving from Kasama in the southwest.
6. 2,300 men led by Hori Hidemasa arriving from Tarao in the northwest.
Standing against this army of 42,000 men were the roughly 10,000 defenders of Iga dispersed throughout the province. Oda’s troops advanced, burning villages, fortresses, shrines, and temples, but meeting relatively little resistance. The most noteworthy martial actions were the seige of Hijiyama fortress which had become the gathering place of Iga’s northern forces, and the seige of Kashiwara fortress in the south. With the surrender of Kashiwara fortress on 8th October, all organised resitance in Iga ended.
Oda Nobunaga himself toured the conquered province at the beginning of November 1581, then withdrew his army, leaving power in his son Nobukatsu’s hands.
Many ninjas managed to survive the desolation of Iga, the most famous being Hattori Hanzo
Hattori Hanzo was a family name in the Hattori clan. The most renowned of them is also known by the name Oni Hanzo or ‛Demon Hanzo’, and he commanded many ninjas in the service of Tokugawa Ieyasu. He became a high-ranking vassal serving the government, and received stewardship of a plot of land worth 8,000 koku. The castle at Edo has a gate which was under the watch of this family. To this day, it is known as Hanzo’s Gate.
The Bujinkan ninja styles survived in the Toda clan which was originally from Iga. Toda Shinryûken Masamitsu (Toda Hisajiro) taught them to Takamatsu Toshitsugu, who instructed Masaaki Hatsumi in these arts.