The Battle of Yamae (Japanese: 山江村の戦い, Hepburn: Yamae-mura notatakai) also known as the Battle of Yakushiyama (Japanese: やくし山の戦い, Hepburn: Yakushi-yama no tatakai) was a battle between the Aso and Sagara clans fought in Autumn, 1531 around the slopes of Yakushiyama. Despite being considerably outnumbered and surrounded, Aso Koretoyo managed to defeat the Sagara army, eventually leading to Sagara Haruhiro’s retreat from Higo Province.
Considered one of Koretoyo’s most impressive victories, the defeat of the Sagara clan is nonetheless seen as a long-term defeat for the Aso, for it brought them into conflict with the far more powerful Shimazu clan.
Background[]
Having pushed back the Kamachi clan to the north of the Yabe River, Aso Koretoyo set about consolidating his rule over northern Higo Province. His first act was that of the construction of several forts along the Midorikawa River, ostensibly to assert authority but likely in fact a preparation for an assault into Southern Higo. The head of the Sagara clan, Haruhiro, considered the act concerning and sent a letter to Koretoyo, demanding the removal of the forts in favour of more open borders. Koretoyo seized upon the opportunity by claiming that Haruhiro wished to invade his own lands and thus struck first, his army crossing the Midorikawa in late summer.
Haruhiro was shocked by such an abrasive act but swiftly prepared his defenses, sending his retainer Katakura Aritoki to defend the city of Yatsushiro. However, upon seeing the fast progress of Koretoyo’s assault, sent another order for Aritoki to surrender Yatsushiro to the advancing Aso forces. As expected, Koretoyo besieged Yatsushiro and Aritoki surrendered after barely a week of assault. So concerned was Koretoyo with reaching and seizing Hitoyoshi Castle, the seat of the Sagara, that he accepted the surrender and continued on his path without securing the city.
The Aso forces then moved south towards Hitoyoshi, eventually passing through Yamae. Here they were confronted with the forces of Sagara Haruhiro, who were encamped along a series of hills south of Yakushiyama. Seeing that the Sagara outnumbered him, Koretoyo encamped upon Yakushiyama to rest and prepare for his assault. However, barely two days after his arrival, another Sagara army arrived from the north. As ordered, Aritoki had left Yatsushiro not long after its surrender and returned to catch the Aso forces in the rear.
Battle[]
Realising his unfavourable position, Koretoyo fortified Yakushiyama and considered his options. Famously his retainer, Akahoshi Kuninaga said “We must leave this hill and go home. There is no honour in defeat,” to which Koretoyo is said to have replied: “Escaping is admitting defeat, but not facing it. This is the greatest disgrace of all.”
As such, in the early morning of the next day, Koretoyo and his men descended the north side of Yakushiyama and attacked the forces of Katakura Aritoki. Despite being outnumbered, Koretoyo’s men were highly disciplined and had the element of surprise. Aritoki was unable to withstand the ferocious assault of the Aso forces and attempted to retreat but fell when his horse was struck by a stray arrow. He was slain by Koretoyo’s men shortly after and his men began to flee north.
Koretoyo did not pursue the retreating forces, instead turning around to face Haruhiro, who had heard the commotion to the north. Haruhiro was apparently under the assumption that Aritoki had attacked too early as he had neglected to even put on his armour in favour of acting swiftly. However, upon seeing the Aso forces already victorious, Haruhiro immediately realised what had happened and ordered a swift retreat to Hitoyoshi. The Aso forces were now moving so quickly, however, that Haruhiro was forced to leave a rearguard of nearly a thousand to cover his retreat. This rearguard was swiftly overwhelmed and Haruhiro barely escaped the battlefield with the small number of men he had left. Luckily, Koretoyo’s forces were exhausted and were unable to pursue, allowing Haruhiro to retreat to Hitoyoshi unmolested.
Aftermath[]
The Sagara forces had been utterly decimated, leaving southern Higo completely under Aso control. Haruhiro spent only two days in Hitoyoshi before abandoning it, aware that he did not have enough men to hold the mountain castle. Instead he fled south to the court of his ally, Shimazu Takahisa. Meanwhile, Koretoyo seized Hitoyoshi Castle, completing his conquest of Higo Province, subsequently proclaiming himself “Lord of Central Kyushu”. However, he had to spend precious months quelling unrest within his newly claimed territories. Whilst the battle of Yamae is considered one of the most impressive tactical victories of the period, it is considered a long term defeat for Koretoyo. This is due to the fact that it brought the Aso into conflict with the far more powerful Shimazu clan, which would ultimately result in Koretoyo’s death at the siege of Aso Castle in 1539.