Siege of Inabayama Castle

稲葉山城の戦い

Oda Clan

Mino Province

Saitō Clan

Date:  8/1 to 8/15 of Eiroku 10 (1567)

Location:  The castle-town of Inokuchi below Inabayama Castle in Mino Province

Outcome:  After earlier attempts that ended in retreat, the Oda army burned down the castle-town of Inokuchi, leaving Inabayama Castle exposed and causing Saitō Tatsuoki to flee down the Nagara River.

Horio Yoshiharu Guiding Hideyoshi to Inabayama Castle

Commanders:  Oda Nobunaga

Forces:  Unknown

Losses:  Unknown

Commanders:  Saitō Tatsuoki

Forces:  Unknown

Losses:  Unknown

The Siege of Inabayama Castle occurred from 8/1 to 8/15 in Eiroku  10 (1567) in Inokuchi in Mino Province.  In this conflict, Oda Nobunaga attacked a garrison commanded by Saitō Tatsuoki based at Inabayama Castle.  Prior to this event, the Oda army had attacked Inabayama on several occasions.  There is a theory that the castle was toppled in Eiroku 7 (1564), but not substantiated based on historical records.

After this battle, Nobunaga renamed Inabayama Castle to Gifu Castle.  Symbolizing a concerted effort to achieve his ambitions, Nobunaga began to use the seal inscribed tenka fubu meaning “command all under heaven through force.”  This is interpreted as meaning the five provinces comprising the Kinai Region.  Meanwhile, this is known as a battle that enabled Kinoshita Tōkichirō (later known as Toyotomi Hideyoshi) to gain prominence.

Background

Inabayama Castle served as the cornerstone for the governance of Mino Province and was designed as an impregnable fortress atop a small mountain.

After the Battle of Kanōguchi, which was waged either on 9/22 of 1544 (or 9/22 of 1547) between Oda Nobuhide (along with Asakura Takakage and Toki Yoriaki) and Saitō Dōsan at Inokuchi, the Oda and Saitō reconciled and entered in a political alliance through the marriage of the daughter of Saitō Dōsan, Kichō (also known as Nōhime), to Nobunaga.  In 1556, after Saitō Dōsan was killed in battle against his son, Saitō Yoshitatsu, the relationship with the Oda deteriorated again.  For a period of time, the Oda and the Saitō frequently engaged in skirmishes, but none of these were decisive.

On 5/19 of 1560, at the Battle of Okehazama, Nobunaga’s army killed Imagawa Yoshimoto (the sengoku daimyō of Suruga Province).  After entering into the Kiyosu Alliance with Tokugawa Ieyasu, he focused on attacking Mino.  On 5/11 of 1561, Yoshitatsu died and was succeeded by his son, Saitō Tatsuoki, at the age of fourteen.  In the sixth and eighth months of 1561, Nobunaga crossed the border into Mino to keep the Saitō in check, but, instead, the Oda were repelled by retainers of the Saitō including Nagai Toshifusa and retreated in defeat.

In the fifth month of 1561, the Oda forces invaded and killed Nagai Toshifusa and Hibino Kiyozane in the course of a victory at the Battle of Moribe.  After prevailing at the Battle of Jūyonjō, Nobunaga rode this momentum to attack Inabayama Castle, but could not capture the fortress and retreated.  In 1563, the Oda invaded eastern Mino but lost fighting against Saitō Tatsuoki at the Battle of Shinkanō.

In 1564, a retainer of the Saitō named Takenaka Shigeharu, together with Andō Morinari, rebelled and took over Inabayama Castle while Tatsuoki abandoned the site.  After occupying the castle for as long as one-half year, they returned it to Tatsuoki.  At this time, Nobunaga had solicited Shigeharu to turn the castle over to him, but Shigeharu refused.  However, this event served to highlight the decline of the Saitō clan and the conspicuous alienation of their retainers.

In 1565, Satō Tadayoshi, the lord of Kajita Castle, betrayed the Saitō in favor of the Oda.  When Kishi Nobuchika, the lord of Dōhora Castle, attempted to attack Kajita Castle, he was killed by the Oda army.  Meanwhile, Nagai Michitoshi, the lord of Seki Castle who acted in concert with Nobuchika, was defeated by Saitō Toshiharu and lost his castle.  As a result, the Oda sphere of influence extended into the central portion of Mino known as the Chūnō region.

In 1566, the settlement that formerly had been entered into between the Oda and the Saitō through mediation by Ashikaga Yoshiaki was spurned and escalated into the Battle of Kōnoshima.  Although Nobunaga lost to Tatsuoki, this represented the final victory of the Saitō clan.

Battle of Inabayama Castle

On 8/1, powerful retainer of the Saitō family known as the Western Mino Group of Three (Inaba Yoshimichi, Andō Morinari, and Ujiie Naomoto) promised to collude with the Oda and were requested to tender a hostage.  While sending Murai Sadakatsu and Shimada Hidemitsu to receive the hostage, Nobunaga quickly assembled troops to invade Mino and rode up Mount Zuiryūji connected in a chain to Mount Inokuchi.  While Tatsuoki’s forces sought to determine whether these were allied or enemy forces, Nobunaga invaded to Inokuchi below the castle and burned down the town, leaving Inabayama Castle exposed.  On this day, the area experienced strong winds.

On 8/14, while deciding assignments for construction, Nobunaga had the forces make branch-twined fences around the perimeter, closing in the castle.  Then, he was surprised by the appearance of the Mino Group of Three who came by for greetings.

On 8/15, locals from Mino surrendered.  Tatsuoki traveled down the Nagara River by boat and escaped to Nagashima in Ise Province.  This result was achieved in just one-half month from the time that Nobunaga raised arms.  Thereafter, Nobunaga changed the name of the locale from Inokuchi to Gifu.

According to the diary of Luís Fróis, a Jesuit missionary residing in Japan during this period, the events unfolded as follows:

After Nobunaga and Tatsuoki set-up their respective camps, Nobunaga devised a plan.  During the night, Nobunaga had one-half of his forces retreat and then secretly take-up positions behind the enemy camp.  After surveiling the Oda camp, Tatsuoki concluded his side was in an advantageous position and commenced an attack.  After Tatsuoki’s forces moved forward, Nobunaga’s battalion stood-up battle flags of retainers of the Saitō that had been made in advance, and circled behind the Saitō army.  Tatsuoki detected this movement, but was relieved to see the flags of allied retainers.  After the outbreak of hostilities, Nobunaga’s battalions launched a pincer attack that inflicted damage on the Saitō and then burst in and toppled Inabayama Castle.  In this way, Nobunaga captured Mino Province.  Meanwhile, Tatsuoki endured significant losses and fled on horseback with several retainers.  First, he went to Kyōto, but later determined it was not safe so went to the metropolis of Sakai.

Timing of the fall of the castle

An authenticated biography of Nobunaga known as the Shinchō kōki does not state the year in which Inabayama Castle fell.  According to other sources, it fell in 1564; however, according to a covenant dated 8/18 of 1566 that was jointly sealed by four elders of the Saitō family, Tatsuoki was doing fine as the head of the family, so the theory based on 1564 is not supported.  With the exception of one document dated 9/15 of 1564 for donations to the Jōzai Temple that requires further investigation, there are no known documents issued by Nobunaga from Gifu Castle prior to the ninth month of 1567.  Prohibitions are concentrated in the ninth and tenth months of 1567.  Moreover, there is a private order from Emperor Ōgimachi dated 11/9 of 1567 ordering Nobunaga to restore the landholdings of the Imperial court surmised to be in Mino.  Meanwhile, a letter dated 9/9 of 1564 from Nobunaga to Naoe Kagetsuna, an elder of the Uesugi family, notes that he attacked Mino, but this is believed to be in a bid to take advantage of the take over of Inabayama Castle that same year by Takenaka Shigeharu.  According to further sources, there is no doubt the Inabayama was toppled by Nobunaga in 1567 while it is difficult to support a theory based on 1564.

Nobunaga moved his base of operations to Inabayama Castle, and changed the name to Gifu Castle.  He destroyed the old territorial boundaries and remodeled the castle.  Further, from this time, he began to use the seal inscribed tenka fubu and direct his efforts toward establishing his hegemony.

After fleeing to Nagashima in Ise, Saitō Tatsuoki joined with the Nagashima Ikkō-ikki religious band in opposition to Nobunaga.  Together with the Miyoshi Group of Three, in the first month of 1569, he participated in the Battle of Honkoku Temple (also known as the Battle of Rokujō) against Ashikaga Yoshiaki and his bakufu army, followed by the Battle of Noda and Fukushima Castles.  Tatsuoki died at the Battle of Tonezaka in 1573 at the age of twenty-six.  There are various theories that he survived until later.

Anecdotes

In this battle, during the invasion of Mino, there is a legend that Hideyoshi constructed Sunomata fortress in a single night to serve as a base for attacks against Inabayama Castle.  As depicted, Horio Yoshiharu served as Hideyoshi’s guide on a back road to Inabayama Castle.

According to folklore, Nobunaga initially delegated construction of the fortress to Sakuma Nobumori, and then to Shibata Katsuie, but failed, and then to Hideyoshi who volunteered for the task.  Hideyoshi floated lumber on rafts from upstream on the Nagara River and in one night (or three days) constructed the fortress which contributed significantly to the attack on Inabayama.  Owing to these achievements, Hideyoshi gained more influence within the family. 

These stories, however, were crafted during the Edo period and therefore not regarded as authentic.