The First Siege of Kuroi Castle occurred from 10/1 of Tenshō 3 (1575) to 1/15 of Tenshō 4 (1576) at Kuroi Castle in the Hikami District of Tanba Province.  During the Azuchi-Momoyama period, Akechi Mitsuhide acted upon orders of Oda Nobunaga to conquer Tanba Province triggering a battle for the base of the Akai clan – the stronghold of Kuroi Castle.  These assaults on the castle occurred twice, with the First Siege of Kuroi Castle in 1575 and the Second Siege of Kuroi Castle in 1579.

Prelude

In the third month of 1570, Akai Tadaie, the head of the Akai family and nephew of Ogino Naomasa, met Oda Nobunaga while Nobunaga was visiting Kyōto and pledged his allegiance.  In response, Nobunaga recognized the rights of the Akai family to the Hikami, Amata, and Ikaruga districts in the interior of Tanba Province.

In the eleventh month of 1571, Isobe Toyonao, a retainer of Yamana Suketoyo (the military governor of Tajima Province) and lord of Isobe Castle, attacked the Adachi clan at Yamagai Castle in the Hikami District.  Naomasa (the lord of Kuroi Castle) and Tadaie headed toward Yamagai Castle in support of the defenders, repelling the Yamana army.  In 1575, Naomasa and Tadaie attacked Takeda Castle in Tajima whereupon Suketoyo turned to Nobunaga to request reinforcements.

During this period, Ashikaga Yoshiaki, the fifteenth shōgun of the Muromachi bakufu, requested support from Naomasa who aligned with Takeda Katsuyori in opposition to Nobunaga.

In the ninth month of 1575, after the Echizen Ikkō-ikki settled down, in the tenth month, acting upon orders of Nobunaga to remove Ogino Naomasa from power, Akechi Mitsuhide invaded Tanaba.

Course of events

Mitsuhide returned from Echizen Province to Sakamato Castle in Ōmi Province and, after finishing preparations, deployed in the tenth month.  At this time, Naomasa was likely residing in Takeda Castle.  After detecting Mitsuhide’s movements, Naomasa returned to Kuroi Castle and prepared for battle.  On 10/1, Nobunaga issued an official letter to Kataoka Tōgorō, a kokujin, or provincial landowner, in Tanba, and ordered him to assist Mitsuhide.  Beginning with Hatano Hideharu of Yakami Castle in the Taki District, a majority of the kunishū in Tanba sided with Mitsuhide.

Mitsuhide set-up positions in twelve or thirteen locations surrounding Kuroi Castle.  At this time, the situation favored Mitsuhide and he confidently stated “The provisions in the castle will not last until next spring so the castle will fall” as the siege progressed in a positive direction.  On 1/15 of Tenshō 4 (1576), over two months after the commencement of hostilities, forces led by Hatano Hideharu suddenly rebelled and attacked the Akechi army from behind, forcing their withdrawal.  During this battle, he lured the enemy into the interior portions of the province and eviscerated them all at once.  This is known as the Akai Entrapment Tactic.

The outcome of this battle was determined by Hideharu’s betrayal so calling this entrapment may not be accurate.  There are questions as to why this terminology was used.  With respect to the response to the letter from Nobunaga, it is noted that the kokujin of Tanba held discussions and may have untruthfully stated: “Naomasa is the only one not to abide by the will of Nobunaga whereas the other kokujin will obey so we desire Naomasa to be eliminated.”  Another account notes: “There was a secret pact between Ogino Naomasa and Hatano Hideharu and the actions were planned.”  Whether this was true is uncertain.  Finally, it is noted: “The Akai and Hatano families were relatives, and although there may have been a secret pact forged in advance, there is no clear record of one.”

Aftermath

On 1/18 of Tenshō 4 (1576), during the withdrawal, Mitsuhide ordered Kobatake Nagaaki to forge a military alliance with the Hayashi clan and to maintain the main base. On 1/21, Mitsuhide went to Kyōto and thereafter returned to Sakamoto Castle in Ōmi.  On 1/29, Nobunaga praised Kawakatsu Tsuguuji for his dedication amidst unfavorable circumstances.  On 2/18, Mitsuhide departed Sakamoto Castle and entered Tanba but departed after a short while.  At this time, the peasants in Sone who cooperated with Mitsuhide were exempted from taxes while he conferred honors and praised Araki Fujiuchi for meritorious service.

Afterwards, Mitsuhide served in numerous battles in the Kinai including the Battle of Tennōji (an attack against the followers of the Ishiyama-Hongan Temple), the Conquest of Kishū (an attack against the Saika Group of Kii), and the Siege of Shigisan Castle.  Consequently, he could not focus his attention on Tanba.  The Akechi army appeared to serve as a detached division sent to various battles on an as-needed basis.

Meanwhile, in the fourth month of 1576, Ogino Naomasa and Akai Tadaie communicated their apologies to Nobunaga and were pardoned.  An official letter from Nobunaga dated 4/13 of Tenshō 4 (1576) to Yano Yasaburō notes that Naomasa and Tadaie apologized so he pardoned them.  The letter further indicates that they would be treated similarly to others who submitted to Nobunaga, retain their fiefs without change.  Yano Yasaburō was in the Kasa District of Tango Province so it is surmised this was meant to convey that the pardon of Naomasa who had deployed to Tango would not be disadvantageous to the Yano clan.  Based on this letter, it can be concluded that, three months after the battle, Naomasa had reconciled with the Oda clan.

Anecdotes

Owing to this battle, Ogino Naomasa became well-known as the Tanba no Akaoni, or the Red Demon of Tanba.  It is surmised that the character “aka” meaning red was derived from his original surname of Akai.  Around this era, it became a customary practice to wear matching armor so Naomasa’s army also may have been adorned in red-colored armor.