Battle of Hachiōji Castle

The Siege of Odawara and a Castle Left Undefended

In Tenshō 18 (1590), Toyotomi Hideyoshi, aiming to unify the realm, dispatched a massive punitive army against the Later Hōjō clan of the Kantō region, and what is known as the Siege of Odawara began. Hojo Ujiteru, an influential kinsman of the Hōjō family who supported the clan's head, Hōjō Ujimasa, and his son Ujinao, had made Hachioji Castle in Tama District, Musashi Province, his base. However, when the campaign began, Ujiteru himself left the castle to join the defense of Odawara Castle, the clan's main stronghold. With Ujiteru absent, Hachioji Castle was left in the hands of his castellan, Yokochi Kenmotsu Yoshinobu, along with senior retainers serving Ujiteru, including Kanō Shuzen'ichian, Nakayama Kageyu Ienori and Kondō Dewa-no-kami Tsunahide. Their forces were limited, and even counting the local residents, including women and children, who had been mobilized or had taken refuge there from the surrounding area, the total is said to have been only about 3,000. With priority given to concentrating forces at the main castle at Odawara, the defenses of Hachioji Castle, an outlying castle, inevitably grew thin. Hachioji Castle was a mountain castle built by Ujiteru, and the scale of its outer enclosure, which included the Oshuden at the foot of the mountain and the castle town, ranked among the largest of the Hōjō branch castles. Yet without sufficient troops, even this strength could not be fully put to use.

Sorties of the Uesugi, Maeda and Sanada Detachments

While surrounding the main castle at Odawara, Hideyoshi also organized detachment forces to defeat the Hōjō-held branch castles of northern Kantō one by one. For the attack on Hachioji Castle, roughly 15,000 troops led by Uesugi Kagekatsu, Maeda Toshiie and Sanada Masayuki were sent from among these detachments. In the predawn hours of the 23rd day of the 6th month of Tenshō 18 (July 24, 1590), the large Toyotomi army advanced under cover of thick fog and attacked the castle simultaneously from two directions: the main approach (Ōte-guchi) on the castle's eastern front at Motohachiōji-machi, and the rear approach (karamete) on the north side at Shimoongata-machi. Facing an army five times their size, the defenders were forced into a desperate defensive struggle.

Outnumbered, the Hōjō defenders resisted fiercely, relying on the steep terrain of the mountain castle. The fighting became a bitter battle that caused many casualties on both sides, but given the overwhelming difference in strength, the defense could not hold out for long. The castellan, Yokochi Kenmotsu, is said to have escaped the castle just before its fall and fled toward Hinohara village, where he took his own life. Nakayama Ienori and other senior retainers of Ujiteru were each killed in action in various parts of the castle. The attacking side is also said to have suffered considerable losses because of the castle's complex terrain and the defenders' resistance, which shows that this was by no means a one-sided battle. Nakayama Ienori died fighting after a valiant struggle, and his martial prowess was highly regarded even by the attackers. It is said that afterward his sons, Terumori and Nobuyoshi, were taken into service by Tokugawa Ieyasu, and the family name was thereby preserved.

A Single Day's Fall, and Its Tragedy

After fierce fighting, Hachioji Castle fell in just one day. As the castle collapsed, many of the women and children trapped inside, having no place to flee, are said to have taken their own lives, some throwing themselves into the falls of the Oshuden within the castle to die. The account has been passed down to later generations as a grim ending. These falls still exist within the castle ruins today, known as 'Oshuden-no-taki,' and they are known as a place where the victims are mourned. After the castle fell, the interior is said to have been thoroughly destroyed by the attacking forces, and there is a view that this also served as a warning to Odawara Castle. The battle of Hachioji Castle is remembered as one of the fiercest of the many fights for the branch castles in the Odawara campaign.

The Impact on Odawara's Surrender

News of the fall of Hachioji Castle dealt a severe blow to the morale of the Hōjō forces holed up in Odawara Castle. The fact that one of their branch castles had been taken in a single day drove home to the Hōjō side the limits of a siege defense, and it is thought to have strengthened the voices calling for negotiation and surrender. Shortly after this report, Odawara Castle surrendered without bloodshed. Meanwhile, the head of the clan, Ujinao, was exiled to Mount Kōya, and Ujiteru, who bore responsibility for the start of the war, was ordered to commit seppuku together with his elder brother Ujimasa on the 11th day of the 7th month of Tenshō 18. With this, the Later Hōjō clan as a warring daimyō house effectively perished, and Hideyoshi's pacification of Kantō, and with it the unification of the realm, was complete. The assault on Hachioji Castle was not merely a local battle but also carried the character of a symbolic engagement marking the end of the Sengoku period itself.

Memories Left at the Castle Ruins

Hachioji Castle's remains are now designated a National Historic Site, and the stone walls of the Oshuden ruins, the hikihashi, and the fortified summit area (yōgai-bu) have been developed and opened to the public. Memorial rites for those who were sacrificed in the fall of the castle have continued to be passed down to the present. As one of the largest castle sieges in the Kantō region at the end of the Sengoku period, the battle is deeply woven into the history of the locality. This mountain castle, built as the stronghold of Hojo Ujiteru, is remembered as one of the stages that symbolize the final phase of Toyotomi Hideyoshi's drive to unify the realm, and it continues to draw many history enthusiasts today. Most of the place names and traditions that remain in the castle town convey the memory of this single day of fierce fighting. The site is also valued as a rare example showing the actual use of Sengoku-period castles in the Kantō region.

Hachiōji After the Fall and Its Succession to Kantō Rule

After the end of the Odawara campaign, the entire Kantō region was granted to Tokugawa Ieyasu, who established his base at Edo and began ruling the Kantō. Hachiōji was also brought under Tokugawa rule. With the Hachiōji Sennin-dōshin, centered on former Takeda retainers and stationed to guard the Kōshū-guchi, the area continued to function as a key point for the defense of Edo throughout the Edo period. The mountain castle itself was abandoned, and the centers of politics and the military shifted to the flatland at its foot. However, the town formed around the castle became the foundation of the later Hachiōji-juku and the Hachiōji castle town, and it developed as a post town along the Kōshū Kaidō in the early modern period and beyond.

The battle of Hachioji Castle, as a contest for Kantō at the very end of the Sengoku period, is often compared with the contests over other Hōjō-held branch castles taken in the same Odawara campaign, such as Oshi Castle and Hachigata Castle. While Oshi Castle is known for the unusual tactic of a water siege by Ishida Mitsunari, Hachioji Castle is often cited, in considering castle warfare in the late Sengoku period, as a contrasting case: a defense that made use of the steep terrain of a mountain castle, against a swift assault by the overwhelming Toyotomi army. Today, through archaeological excavations, the remains of the Oshuden site and Shiroyama are gradually revealing their appearance at the time, and they have become important subjects of research for both the history of Sengoku-period castles and the history of the Kantō region.

Through postwar excavations, the Oshuden site has yielded many footing stones from buildings burned in the fire, along with ceramics and metal objects believed to have been used at the time, and these are attracting attention as material evidence of the ferocity of the castle's fall. The Hachioji Castle ruins are now also beloved as a hiking course visited by many mountaineers and history enthusiasts, and the installation of information boards and interpretive facilities conveying the fighting of the time is also progressing.

This battle is also often cited later as an example of the limits of mountain castles as defensive installations. Even Hachioji Castle, which boasted a nawabari (layout) exploiting its steep terrain, could fall in a single day when the overwhelming difference in troops coincided with the absence of its lord. This is regarded as an important example for considering the turning point in castle tactics at the end of the Sengoku period. Throughout the Edo period thereafter, large mountain castles were almost never newly built in the Kantō region, and this is also positioned as one background to the shift of the mainstream of castle building toward early modern castles built on flat ground.

Today, Hōshōji Temple continues to hold memorial services for the victims of the castle's fall, and the area around the Oshuden-no-taki is cherished as a place of quiet prayer. The Hachioji Castle ruins have been selected as one of Japan's 100 Famous Castles, and they are also included among the constituent cultural properties of the Agency for Cultural Affairs' Japan Heritage designation 'Reiki Manzan Takaosan,' and their value as remains of Sengoku-period castles is highly regarded.

The battle of Hachioji Castle has been repeatedly taken up in later war chronicles (gunkimono) and local histories as a battle symbolizing the final stage of Toyotomi Hideyoshi's nationwide unification enterprise. The stubborn resistance kept up to the very end by the castellan and senior retainers, under the disadvantage of the lord's absence, is passed down in local tradition as a demonstration of the pride of Hōjō warriors, and even today it remains one of the important subjects in local history education in Hachiōji.