Hōsatsu War

豊薩合戦

Shimazu Clan

Bungo Province

Ōtomo Clan

Date:  Tenth month of Tenshō 14 (1586) to third month of Tenshō 15 (1587)

Location:  Multiple locations across Bungo Province in Kyūshū

Synopsis:  The Shimazu clan defeated the Ryūzōji clan in 1584, leaving the Ōtomo clan of Bungo Province as the sole remaining power in Kyūshū preventing the Shimazu from controlling the entire island.  This led Shimazu Yoshihisa to send forces north from Satsuma to invade Bungo, triggering a multitude of battles against the Ōtomo across Bungo over approximately a one-half year period.  The Shimazu forces ultimately withdrew to their home province of Satsuma on the eve of a campaign led by Toyotomi Hideyoshi known as the Kyūshū Pacification.

Shimazu Yoshihisa

Ōtomo Sōrin

Lord:  Shimazu Yoshihisa

Commanders:  Shimazu Iehisa, Shimazu Yoshihiro, Niiro Tadamoto, Ishūin Hisanobu

Forces:  Varies by battle

Losses:  Varies by battle

Lords:  Ōtomo Yoshishige (Sōrin), Ōtomo Yoshimune

Commanders:  Yamada Munemasa, Toshimitsu Sōgyo, Saeki Koresada, Sengoku Hidehisa, Sogō Masayasu, Chōsokabe Motochika

Forces:  Varies by battle

Losses:  Varies by battle

The Hōsatsu War occurred from Tenshō 14 (1586) to Tenshō 15 (1587) in Bungo Province and was waged between the Ōtomo clan of Bungo and the Shimazu clan of Satsuma Province.  This conflict is also referred to as the Tenshō Campaign or Tenshō War based on the name of the era in which it occurred.  The term “Hōsatsu” refers to Bungo and Satsuma provinces.

Relationship of the Ōtomo and Shimazu clan during the Tenshō era (1573 to 1593)

In the tenth month of 1578, Ōtomo Yoshimune (the head of the Ōtomo family) and his retired father, Ōtomo Yoshishige (Sōrin) led a large army on a southward march on the pretext of a request from Itō Yoshisuke, the sengoku daimyō of Hyūga Province.  In an event known as the Battle of Mimikawa at the Takagi River in Hyūga, however, this army was routed by the forces of Shimazu Yoshihisa and lost many commanders and soldiers, including Saeki Korenori and Saeki Korenao (father and son) and Yoshioka Yoshioki, upon which Sōrin retreated to Bungo.

Owing to this major defeat, Ryūzōji Takanobu of Hizen Province (who had until this time obeyed the Ōtomo family) separated and became independent.  Moreover, in Chikuzen Province, Akizuki Tanezane and Tsukushi Hirokado switched their allegiance from the Ōtomo to the Shimazu family.  In addition, mainstays of an illegitimate branch of the Ōtomo including Tahara Chikahiro, Tahara Chikatsura, and Takita Shōtetsu initiated a rebellion against the Ōtomo.  This was followed by revolts across the territory held by the Ōtomo spanning the provinces of Bungo, Chikuzen, Hizen, Chikugo, Buzen, and Higo.

Meanwhile, the Shimazu family took advantage of their overwhelming victory at Mimikawa to take control of Satsuma, Ōsumi, and Hyūga, extending their reach into Higo and increasing their pressure upon the Ōtomo family.  Owing to a series of revolts within their territory, the Ōtomo could not resist on their own so the clan approached Oda Nobunaga, who was expanding his power in the Kinai and beyond.  Even after the fall of Funai Castle, the Ōtomo continued to stiffly resist and counterattacked the Shimazu army throughout the region.  In 1579, through the offices of Nobunaga, Yoshimune was invested with an official title and, in 1580, through the mediation of Nobunaga, a settlement was reached with Yoshihisa known as the Hōsatsu Reconciliation (meaning the reconciliation between Bungo and Satsuma provinces).

On 6/2 of Tenshō 10 (1582), Nobunaga died in a coup d’état known as the Honnō Temple Incident launched by a senior retainer, Akechi Mitsuhide.  This caused the end of the Hōsatsu reconciliation.  In the third month of 1584, Ryūzōji Takanobu was killed in action during a loss to the Shimazu army at the Battle of Okitanawate.  His eldest son, Ryūzōji Masaie, surrendered to the Shimazu family, bringing to an end the era of the three-way contest between the Ōtomo, the Ryūzōji, and the Shimazu clans of Kyūshū formed after Mimikawa.  In turn, this marked the advent of a two-way contest for hegemony in Kyūshū between the Ōtomo and the Shimazu clans.

After the death of Ryūzōji Takanobu, Sōrin had forces from Chikuzen including Tachibana Dōsetsu and Takahashi Jōun advance into Chikugo in an effort to contain the influence of the Shimazu family.  Yoshihisa responded by decimating the Aso clan of Higo who were retainers of the Ōtomo in an event known as the Battle of Aso.  He then had Akizuki Tanezane and Ryūzōji Ieharu advance into Chikugo to confront Dōsetsu on Mount Kōra.  During this stand-off, however, on 9/11 of Tenshō 13 (1585), Dōsetsu died owing to his old age, whereupon the Ōtomo army retreated to Chikuzen.  The death of Dōsetsu represented the loss of a main pillar of the Ōtomo family.  As a result, Sōrin turned to Toyotomi Hideyoshi who had inherited the work of Oda Nobunaga to unify Japan, pledged his allegiance, and requested reinforcements.  Hideyoshi, however, was engaged in battle against Tokugawa Ieyasu of Mikawa, so he could not spare reinforcements at this time.  Therefore, similar to Nobunaga, Hideyoshi intervened politically for a resolution of the conflict, but Yoshihisa refused to settle.

The Shimazu family used the death of Dōsetsu as an opening to advance into Chikuzen.  Chikuzen was the base of powerful figures aligned with the Ōtomo including Tachibana Muneshige of Tachibanayama Castle, Takahashi Jōun of Iwaya Castle, and Takahashi Munemasu (Tachibana Naotsugu) of Hōman Castle.  Without their elimination, these forces posed a potential barrier to invading the home territory of the Ōtomo family in Bungo.  Yoshihisa assigned Shimazu Tadanaga (a younger cousin and veteran who was the lord of the manor of Kushira in Ōsumi Province) to serve as the commanding general of the Shimazu army to attack Iwaya Castle in an event known as the Siege of Iwaya Castle.  Takahashi Joun resisted valiantly but it was to no avail and Iwaya Castle was toppled.  During the assault, the Shimazu army incurred many casualties.  Although Hōman Castle was also felled, Tachibana Muneshige held Tachibanayama Castle and, owing to the severe drain on their resources, the Shimazu army returned to Satsuma.

With the death of Jōun, the threat posed by the forces from Chikuzen was removed.  After reorganizing their forces, in the middle of the tenth month of 1586, the Shimazu family commenced attacks with Shimazu Yoshihiro leading an army of 30,000 troops from the Higo road and Shimazu Iehisa leading 10,000 troops from the Hyūga road.

Attacks by the Shimazu clan

Invasion of Bungo Province

The army of 30,000 troops led by Yoshihiro invaded Bungo from the Higo road.  In connection with this invasion, senior retainers of the Ōtomo including Nyūta Yoshizane and Shiga Chikanori betrayed the Ōtomo in favor of the Shimazu and served as guides for Yoshihiro in Bungo.

Beginning on 10/22 by toppling Taka Castle (defended by Sada Tsunetō, a retainer of Shiga Chikatsugu) after cutting off the aqueducts​, the Shimazu forces captured numerous castles in the Ōno District including Karasudake Castle (during which Hori Sagami-no-kami was killed in action), Tsugamure Castle (during which Bekki Munesada surrendered), Takao Castle (during which Hori Nakatsukasa surrendered).  Other sites toppled included Katagase, Tanaka, and Komaki castles, but Oka Castle, defended by Chikanori’s eldest son, Shiga Tarō-Chikatsugu, did not fall despite incurring a major assault by a large Shimazu army.  Oka Castle was situated atop an 80-meter hill surrounded by the Ōno, the Inaba, and the Tamarai rivers serving as natural moats.  During a ferocious battle against Chikatsugu, the Shimazu also incurred losses.

Battle of Dabaru Castle

Yoshihiro assigned soldiers to protect Oka Castle and then captured outlying castles.  With respect to Kimure Castle, however, he failed and, at Dabaru Castle, owing to the ingenious tactics of Asakura Kazuharu, Sakase Buzen-no-kami of the Shimazu army was killed when a fire erupted at the castle by means of a delayed fuse.  At Sasaharame Castle, Shirasaka Iwami-no-kami was killed through the use of deceptive tactics by Anami Korehide.

Battle of Yamano Castle

Niiro Tadamoto, the commander of the largest division under Yoshihiro, toppled Minamiyama Castle and entered the Naoiri District, attacking Kutami Akiyasu at Yamano Castle.  Although, at this time, Akiyasu was eighty-five years old, he stood firm against the Shimazu army.  Akiyasu’s eldest son, Kutami Shigenori, was in charge of defending the outlying Mifune Castle, but evacuated to Yamano instead, seeking refuge with his father.  Even after the fall of Mifune Castle, Akiyasu did not flinch, but, despite commanding forces at his advanced age, he died of illness on 12/23 of Tenshō 14 (1586).  On the next day, Shigenori surrendered and vacated Yamano Castle.  According to one source, Akiyasu was indignant at Shigenori’s contemplation of a settlement, and died thereafter.

Battle of Asahidake and Togamure Castles

As the Shimazu army under Iehisa invaded Bungo from the Hyūga road, Asahidake Castle was on the front line, defended by Shibata Shōan, a senior retainer of the Ōtomo clan.  Shōan surrendered without a fight.  As a result, Togamure Castle defended by Saeki Koresada (Korenao’s son) became the new front line.  On 11/4, Koresada was joined on Mount Hachiman by Yamada Munemasa (a guest commander from the Itō clan) to engage in a field battle against Iehisa’s army.  Despite inferior numbers, Koresada prevailed in this event known as the Battle of Katata.

Next, the Ōtomo directed Koresada toward Shibata Shōan for surrendering to the Shimazu without a fight.  Meanwhile, Iehisa was suspicious of Shōan’s true intentions so did not rely upon and did not respond to appeals from Shōan to send reinforcements to his base at Hoshiko Castle.  Originally, surrender to the Shimazu clan appeared to be an individual act of Shōan.  On 12/4, Hoshiko Castle fell after a bushō colluded with Koresada and the Shibata family was slaughtered.  Shōan despised Iehisa for refusing to send reinforcements and rebelled against the Shimazu, but was soon suppressed and killed.

Battle of Inbi Fortress

Inbi fortress was built from a cavern and could not be captured by the Shimazu army.  After Iehisa toppled a stronghold in the Ōno District known as Matsuo Castle, his forces headed north alongside the Banjō River in the direction of Togamure Castle.  Upon hearing of the arrival of the Shimazu army, local peasants holed-up in the fortress and resisted.  The Shimazu forces withdrew without capturing this fortress.

Battle of Tsuruga Castle

Owing to a robust defense by Saeki Koresada and Yamada Munemasa, Iehisa relinquished efforts to capture Togamure Castle and directed his forces toward Tsuruga Castle.  Tsuruga was a stronghold located between Sōrin’s base at Usuki Castle and Yoshimune’s base at Funai Castle and defended by Toshimitsu Sōgyo, a renowned bushō in the Ōtomo family.  Despite being significantly outnumbered, on 11/26, the forces accompanying Sōgyo launched a nighttime attack that scattered the Shimazu army.  On 12/3, Iehisa launched an all-out attack that resulted in the death of a close associate of Sōgyu named Satō Mimasaka-no-kami in the course of a prolonged battle.  On 12/6, in a ferocious assault, the Shimazu forces breached the outer perimeter and citadel of the castle, during which Asami Kageharu (one of the defending troops) was killed.  On 12/7, Sōgyu died fighting in a battle for control of the main citadel.  Nevertheless, stiff resistance by Sōgyu’s younger brother, Seidiaji Gōei, prevented the fall of the castle.

Counterattacks by the Ōtomo

Battle of Hetsugigawa

In response to requests for reinforcements at Tsuruga Castle, Yoshimune promptly departed with troops.  At this time, the Ōtomo army at Funai Castle was joined by vanguard forces sent as reinforcements by Toyotomi Hideyoshi, including Sogō Masayasu from Sogō Castle in Sanuki Province, Chōsokabe Motochika and Chōsokabe Nobuchika (father and son) from Tosa Province, and Sengoku Hidehisa from Takamatsu Castle in Sanuki.  All together, these forces outnumbered the Shimazu army led by Iehisa.  On 12/12, the Ōtomo army established a position at Kagami Castle across the Hetsugi River to the west of Tsuruga Castle.  At the war council held at this time, Hidehisa firmly insisted that the forces launch an attack.  Masayasu, along with the Chōsokabe, opposed him, favoring a more conservative strategy.  In the past, the Sengoku, the Sogō, and the Chōsokabe fought against one another in Shikoku, resulting in lingering hostilities among the clans.  Unable to form a united opposition to the proponents of an offensive, the opinions of Yoshimune who sought to rush to the aid of Tsuruga Castle and Hidehisa, who exercised the authority of a general of the Toyotomi army, the Ōtomo army decided to attack the Shimazu forces, triggering the Battle of Hetsugigawa.

Iehisa deployed a strategy devised by the Shimazu by which to lure and ambush the opposing forces in a field battle.  To implement the strategy, the forces were divided into three battalions. Two of these battalions concealed themselves on the flanks.  He then assigned Ishūin Hisanobu to lead the rear guard while the third battalion intentionally pulled back, serving to lure the Ōtomo forces forward.  Meanwhile, Iehisa, along with Niiro Daizen and Yamada Arinobu established positions on the flanks.  At the opportune time, these two battalions closed in from the flanks while the retreating battalion defended by Hisanobu turned around to charge from the front, resulting in a three-pronged attack that devastated the Ōtomo.  Among the commanders killed in action were Sogō Masayasu, Chōsokabe Nobuchika and Bekki Munetsune.  As an outcome of this loss by the Ōtomo, the defenders at Tsuruga Castle surrendered to Iehisa.

Battle of Funai Castle

Riding the momentum of his major victory at the Battle of Hetsugigawa, Iehisa toppled Kagami Castle and Odake Castle, proceeded north, and, on 12/13, overran Funai Castle, the primary base of the Ōtomo family.  The castle fell in just one day because Ōtomo Yoshimune avoided a fight and instead fled north to Takasakisan Castle near the provincial border with Buzen.  At the time, Yoshimune requested reinforcements from Mōri Terumoto and his military commander, Kuroda Yoshitaka, who were in Buzen at this time.

Battle of Usuki Castle

Usuki Castle, also known as Niujima Castle, was built by Ōtomo Sōrin in 1562.  The castle was located on Niu Island which has the shape of a sandal.  The castle was connected to the mainland only at the time of low tide.  As a result, except during periods of low tide, an assault on the castle required naval forces.  Iehisa could not rely solely on his superior forces to mount an assault on this castle.  Meanwhile, large cannons that Sōrin acquired from Portuguese traders wreaked havoc on the Shimazu army.  In the end, Iehisa did not topple Usuki Castle and was forced to withdraw.

Battle of Tsurusaki Castle

In connection with efforts to topple Usuki Castle, Iehisa assigned Ijūin Hisanobu, Nomura Fumitsuna, and Shirahama Shigemasa to capture the outlying base of Tsurusaki Castle.  This castle was defended by Yoshioka Munemasu (the eldest son of Wakabayashi Shigeoki) but Munemasu was cornered in Usuki Castle, so Tsurusaki was defended by his mother, Myōrin-ni, who was a nun.  Through the use of ingenious tactics including hidden traps, Myōrin-ni imposed significant losses upon the Shimazu forces, but, after their provisions dwindled, the defenders were forced to surrender.  At this time, members of the Shimazu army and the defenders shared a banquet to make amends, but in the third month of 1587, an order to retreat arrived from Iehisa.  In the preceding year, Hideyoshi compelled Tokugawa Ieyasu to visit Kyōto to pledge his allegiance and then dispatched a large army from the Kinai to Kyūshū.  As a result, the Shimazu army withdrew, but Myōrin-ni was waiting for an opportunity to counterattack so, after the Shimazu forces arrived near Otozu River, she launched a surprise attack.  In the ensuing battle, Hisanobu and Shigemasa were killed, while Fumitsuna was wounded and, although managed to escape with help from allies, later died.

Battle of Hijū Castle

The main division under Yoshihiro felled Yamano Castle, followed by Shigemi Castle, Matsugao Castle, and Funegao Castle in the Anami township, pacifying the Ōita and Kusu districts of Bungo.  Shiga Chikatsugu of Oka Castle, however, engaged in skillful guerilla tactics to impede the main division of the Shimazu army under Yoshihiro.  This caused Yoshihiro to have Niiro Tadamoto organize a detached wing to suppress the two districts.  This battalion proceeded to topple Inui Castle, Kusu Castle, and Shirogao Castle, but, at Tsunomure Castle, the forces were halted by an expert archer named Shukuri Geki and retreated.

At Hijū Castle, the lord of the castle named Hoashi Akinao and his wife, Onigozen, charged out of the castle and launched a surprise attack against the army of Niiro Tadamoto while the soldiers were resting at Tsunomure Castle.  Owing to the contributions of Onigozen, the scattered in disarray and Tadamoto himself incurred injuries before fleeing in defeat.

Withdrawal

At the end of 1586, after Hideyoshi compelled Tokugawa Ieyasu to visit Kyōto to pledge his allegiance, beginning in 1587, Hideyoshi directed a large army toward Kyūshū for a campaign known as the Kyūshū Pacification.  As a result, without having brought Bungo under its full control, in the third month, the Shimazu army withdrew.  During the withdrawal, the Shimazu incurred further losses owing to attacks by forces under the command of Shiga Chikatsugu and Saeki Koresada.

Thereafter, in the fourth month of 1587, at the Battle of Nejirozaka in Hyūga Province, the main division of the Shimazu army lost and surrendered to Toyotomi clan as a key milestone of the Kyūshū Pacification.