Mt. Shosha and the Taiko Residence (3)

──How did the sacred site of faith transform into the "Harima Campaign Headquarters"?
──The temple fortress as the Harima Campaign Headquarters
──Hideyoshi turned the "mountain temple" into the heart of the Harima campaign

In my previous writings, "Harima Province and Mt. Shosha (1)" and "Mt. Shosha Engyoji Temple (2)," I examined the cultural influence that Mt. Shosha Engyoji possessed in the Middle Ages, as well as its inclusivity as an "asylum" (sanctuary) where secular power could not intervene.

Since its founding by Priest Shoku, this mountain religious city had gathered much faith and absorbed legends of figures such as Izumi Shikibu, Musashibo Benkei, and even Retired Emperor Go-Shirakawa and Emperor Go-Daigo, maintaining its peace as a "realm of gods and Buddhas" beyond the reach of secular rule.

However, in March of Tensho 6 (1578), this sanctuary was forced into "fortification" due to the invasion of Harima by Hashiba Hideyoshi, acting under the orders of Oda Nobunaga, who aimed to unify the country. A massive army of approximately 20,000 soldiers stormed the mountain, high-ranking priests and monks who had been training were driven off the mountain, and temple treasures and utensils were looted by the subordinate soldiers. As a symbol of this harsh military occupation, a headquarters was established at the Juchi-bo sub-temple of Engyoji, and the ruins known as the "Taiko Residence" remain on the mountain as a scar of this event.

In this content, while inheriting the context of Engyoji as an asylum presented thus far, I will three-dimensionally unravel the reality of Mt. Shosha as a military fortress during the Sengoku period through the analysis of the newly discovered historical document "Copy of a Letter by Hashiba Hideyoshi in Tensho 8" published in 2024 and the "Shinchoki," as well as an examination of the ruins of the "Taiko Residence (Hakusan Castle)" remaining on the mountain.

1. The true image of the "Taiko Residence": Stripping away the false image of a mansion

In the mountains behind the "San-no-do" of Mt. Shosha Engyoji, on the flat land on the south side of the west peak of Hakusan Gongen, the highest point, there are ruins called the "Taiko Residence." This romantic name evokes the image of a stylish (neat, refined, and not vulgar) mansion or a villa for rest built by Toyotomi Hideyoshi, who later became the ruler of the country, out of nostalgia for his past Harima campaign. However, this is merely a historical illusion of later generations.

At the time of the Harima invasion in Tensho 6 (1578), Hideyoshi was not yet the "Taiko," but "Hashiba Chikuzen-no-kami," a general of the Oda clan. The "Taiko Residence" in reality was not an elegant palace, but a practical field headquarters built to counter the massive army of Mori Terumoto and the rebellion of the Bessho clan, a prestigious family in East Harima—in other words, it was the "Harima Campaign Headquarters (Castle of the Harima Inspector)" itself.

As the physical center of his military occupation, which lasted about two years, Hideyoshi requisitioned the "Juchi-bo," a sub-temple of Engyoji that occupied a vast site on the west side of the Kaizan-do, and established his headquarters (military command post). The Juchi-bo, which had been a place of quiet training, was converted into a military command center to lead tens of thousands of troops, and the vast temple territory, said to be 27,000 koku, was confiscated. The flat land where a concrete water tank is currently installed was the site of the "operations headquarters" that once moved the Sengoku history of Harima.

2. Why was it Mt. Shosha?

To understand why Hideyoshi chose the steep Mt. Shosha as his headquarters for the Harima campaign, it is necessary to examine both the description in the primary historical source "Shinchoki" and the political dynamics.

The entry for February 23, Tensho 6, in the "Shinchoki" written by Ota Gyuichi contains the following description.

This description shows that from the early stages of starting the Harima campaign, Hideyoshi had the intention of building a "fortress (military stronghold)" on Mt. Shosha and using it as a long-term garrison. So why did he choose Mt. Shosha instead of other flatland castles or the nearby Himeji Castle? The reasons can be summarized into the following three points.

First is the capacity to accommodate a large army and its natural defensive power. While Mt. Shosha's steep terrain acted as a barrier to prevent surprise attacks from the foot of the mountain, the vast temple space (the three hundred halls of the mountain) spread out on the summit, making it possible to safely accommodate tens of thousands of soldiers, warhorses, and provisions.

Second is the ability to monitor the Harima Plain. From the summit, which is over 370 meters above sea level, one could overlook everything from the Himeji Plain to the Seto Inland Sea, and even the movements of East Harima, the base of the Bessho clan, allowing for the grasp of military information in real time.

Third, and decisively, is the north-south geopolitical confrontation with Ega Castle, centered on the Yumesaki River. At the time, Ega Castle, a major stronghold for anti-Oda forces (pro-Mori faction and Hongan-ji followers) in Harima, was a port town located at the mouth of the Yumesaki River, controlling maritime communication routes with the Mori navy and the Osaka Hongan-ji. Mt. Shosha is located at the uppermost reaches (northern stronghold) of this Yumesaki River. Hideyoshi's occupation of Mt. Shosha meant controlling the water transport of the Yumesaki River and cutting off and suppressing Ega Castle from both land and water from upstream.

Furthermore, the newly discovered historical document "Copy of a Letter from Hashiba Hideyoshi in the 8th Year of Tensho," published in February 2024 by the Hyogo Prefectural Museum of History and the Historiographical Institute of the University of Tokyo, reveals a surprising turning point hidden in the occupation of Mt. Shosha. Based on the descriptions in this letter, the following comparison table organizes the composition leading up to Hideyoshi's "castle breaking" in Harima and the occupation of Mt. Shosha.

• Kasuya (Kakogawa) Castle (Kasuya Naizen, Kasuya Takenori) - Originally a target for Hideyoshi's castle breaking (demolition), but was the only one to refuse demolition due to Bessho's resistance. - Functioned as the main logistics base for Hideyoshi's Harima campaign.

• Kajiwara (Takasago) Castle (Kajiwara clan, naval forces) - Based in the coastal area of East Harima, communicated with the Mori navy. Hideyoshi ordered Bessho Nagaharu to submit "additional hostages" from the Kajiwara clan. - Refused to submit additional hostages and colluded with the Mori side along with Bessho Nagaharu.

• Bessho Yamashiro-no-kami (Yoshichika) (Takao-yama Castle) - A powerful branch castle lord of Miki Castle and a spearhead of the pro-Mori faction. Hideyoshi ordered Nagaharu to submit "additional hostages" from Yoshichika. - Refused to submit hostages. Later became the center of the hardline faction in the Battle of Miki.

• Bessho Nagaharu (Lord of Miki Castle) - Offered a deal that if he submitted the additional hostages of the Kajiwara clan and Bessho Yoshichika, he would be given Kasuya (Kakogawa) Castle, which had been exempted from demolition. - Refused the deal (broke the promise). As a result, he was "driven out" of Mt. Shosha by Hideyoshi.

In conventional explanations, Bessho Nagaharu's defection was attributed to an emotional conflict (an argument at the Kakogawa Council). However, the new historical documents show that the "castle breaking" policy that Hideyoshi had been promoting immediately after the invasion of Harima (from the end of Tensho 5 to the beginning of Tensho 6) was the trigger for the confrontation. Hideyoshi demanded that Nagaharu submit "additional hostages" from the Kajiwara clan and Bessho Yoshichika, who were suspected of collusion, and attempted a divide-and-conquer strategy by offering control of Kasuya (Kakogawa) Castle in exchange. However, Nagaharu rejected this demand.

In response to this breach of promise by the Bessho side, Hideyoshi carried out a show of military force. He "drove them out" of Mt. Shosha, which was under the influence of the Bessho clan (or under the control of pro-Bessho monks) at the time, and turned it into his own "residence (military occupation)." Nagaharu and his group, feeling dissatisfied and threatened by the fact of Hideyoshi's occupation of Mt. Shosha, left the negotiating table, abandoned their camp, fled to Miki Castle, and embarked on rebellion. The occupation of Mt. Shosha was not a movement of the main camp due to the Bessho clan's defection, but an "active military sabotage" that dragged the Bessho clan into a decisive battle.

3. Fortification of the Temple

The essence of Hideyoshi's occupation of Mt. Shosha lies in the instantaneous functional conversion (hacking) of a "religious space" into a "modern military fortress" exactly as it was.

In medieval Japan, temples were "asylums" (sanctuaries) where secular laws did not reach, and were inviolable domains where the police power or military force of a feudal lord could not easily intervene. Engyo-ji was also a sanctuary that had protected such peace, but Hideyoshi destroyed this asylum. Hideyoshi drove out most of the monks who had maintained each sub-temple until then, and quartered about 20,000 of his soldiers in each building. This was based on rationalism, saving the need to build large-scale barracks (camp huts) from scratch and reusing the sturdy building complex as barracks as it was.

Furthermore, the looting of temple treasures and the confiscation of temple lands were not just financial seizures, but also violence to strip away religious authority and subordinate them to the unified secular power (Oda/Toyotomi regime). Hideyoshi forcibly seized the temple buildings and the potential as a religious city that had been built over hundreds of years, and transformed them into military infrastructure to establish his hegemony.

4. Layout of the Taiko Residence

A castle ruin was built with Juchi-bo as Hideyoshi's command headquarters. This is the reality of the ruin now called the "Taiko Residence." The layout (castle design plan) of this Hakusan Castle (Taiko Residence) has the structure of the late Sengoku period, despite being a short-term field castle. Its main sections and structural features are classified as follows.

• Main Enclosure (East Enclosure) - Located at the highest point on the west peak of Hakusan Gongen. Almost the entire circumference, excluding the passage, is surrounded by sturdy high earthen ramparts. - The place of supreme decision-making for commanding the Harima campaign (Hideyoshi's residence), and the center of the main camp.

• Second Enclosure (West Enclosure) - Adjacent to the west side of the main enclosure, spreading out at a lower level. A strong defensive section with earthen ramparts like the main enclosure. - A garrison for commander-class mounted guards and close soldiers who formed the main force.

• Koguchi (Entrance) –A narrow opening created at the boundary between the main enclosure and the second enclosure. It features a crank-shaped bend. – An interception barrier designed to limit the movement of invading enemies and defeat them individually.

• Surrounding flat land –Flat surfaces spreading out in a stepped fashion on the south side of the main enclosure and the surrounding slopes. These are the sites of former sub-temples such as Sengaku-in and Kanayama-in. – An improvised barracks for housing and stationing a large army of over 20,000 without the need for new construction.

The 'earthen ramparts' that surround the main enclosure in an almost complete circle were important as a shield to protect against arrows and bullets from surprise attacks by the Mori and Bessho forces climbing from the foot of the mountain, and also as firing positions for the defenders. Hideyoshi's layout plan, which functionally repurposed these sub-temple sites and flat spaces as barracks, material storage, and even water supply bases (such as the water tank at Juchibo), effectively utilized the existing temple topography.

5. The 'Showcase Stone Walls' around Maniden

Around the 'Maniden (Nyoirin-do Hall)', which is the main hall of Engyo-ji Temple, there are moss-covered, atmospheric stone walls that delight the eyes of visitors. In particular, at the lower part of the Maniden, near the entrance from the approach to the temple grounds, exceptionally prominent 'megaliths' are placed. One can strongly feel the intention of these being 'showcase stone walls' designed to project a sense of presence to those passing by.

In the 'Oda-Toyotomi style castles' (such as Azuchi Castle and the early modern Himeji Castle) built by Oda Nobunaga and Hashiba Hideyoshi in the late Sengoku period, a technique of placing huge stones called 'mirror stones' around castle gates and castle towers to flaunt power was favored. At first glance, it seems one could interpret these stone walls around the Maniden, which feature such megaliths, as having been built by Hideyoshi to show off his authority and make the approach to his headquarters (Juchibo) full of dignity. However, observing the 'technical characteristics' of the stone walls reveals that they were not built by the castle stonemasons (such as the early modern Anoshu) dispatched by Hideyoshi.

The greatest feature of the stone walls of Oda-Toyotomi style castles is the 'sangi-zumi' (alternate stacking) technique, where the long and short sides of rectangular cut stones are stacked alternately to increase the strength of the corners. However, the corners of the stone walls around the Maniden are not built with sangi-zumi, and they use a classical stacking method that differs in both strength and technique.

Based on the technical characteristics above, the stone walls around the Maniden may have been built by local temple stonemasons out of religious and architectural necessity as a 'leveled foundation' to secure the massive stage-style (kake-zukuri) Maniden on the mountainside during the medieval period. Hideyoshi brilliantly borrowed (hacked) the intimidating presence and authoritative space emitted by these existing medieval temple 'showcase stone walls (megaliths)' and used them as a dignified approach to his supreme headquarters (Juchibo) for demonstrations to soldiers and visitors.

6. Military use of the bell tower

In the fortification of Mt. Shosha, the 'bell tower,' which is designated as an Important Cultural Property, was repurposed as an 'existing religious facility' not found in hastily constructed field castles.

This bell tower is a two-story structure (ro-zukuri) with a hakama-goshi (flared base), estimated to have been rebuilt in the late Kamakura period (first half of the 14th century). At first glance, it appears to be an elegant piece of Buddhist architecture lacking defensive features (such as stone drops or loopholes), but its structure and facilities were useful as a practical 'combined watchtower and signaling turret' during wartime.

The upper level of the two-story structure is a raised-floor design, ensuring an excellent field of vision with nothing to obstruct the surroundings. This could serve the same role as a 'corner turret' or 'watchtower' in a castle, allowing for the monitoring of the castle road at the foot of the mountain or the detection of enemy forces attempting to invade from the Yumesaki River. Furthermore, the temple bell, said to have been recast in the first year of Genko (1324), was normally used to signal the times for religious practice, but in times of emergency, it became a wide-area signaling system that could instantly send signals of 'enemy attack' or 'assemble' to the approximately 20,000 Oda soldiers scattered across the mountain. Just as temple bells and drums (drum towers) were utilized as defensive alarm systems for civilian fortresses in late medieval temple towns (such as Ega), Hideyoshi also made full use of this acoustic wide-area communication network in the Harima pacification campaign.

7. Conclusion

The historical clarification of the 'Taiko Residence' and 'Hakusan Castle' remaining on Mt. Shosha Engyo-ji rejects the romanticized image of the Sengoku period held until now and confronts us with geopolitical and technical realities.

First is the fact that the 'Taiko Residence' was not an elegant mansion, but rather the 'Harima Conquest Command Headquarters (Supreme Military Operations Headquarters)' that controlled the Harima campaign. Hideyoshi requisitioned 'Juchi-bo,' a prominent sub-temple, and stationed troops there for two years, using it as a base to drive the pacification of Harima.

Second, Hideyoshi did not build a new castle here; rather, he dismantled a religious asylum (sanctuary) that boasted a thousand-year tradition and 'hacked' (militarily repurposed) its spatial and facility potential. By driving out the monks and looting or confiscating temple treasures, he stripped away the authority of the sacred, reorganized existing flat lands (leveled ground) into barracks, turned the giant stone walls of the Maniden into an intimidating approach, and repurposed the bell tower with its hakama-goshi into a military watchtower and signaling post.

Third is the political dynamic of the forced occupation of Mt. Shosha, revealed by the 'Hashiba Hideyoshi Letter Copy' published in 2024. The 'castle breaking' (destruction of fortifications) that Hideyoshi enforced and the breakdown in negotiations over the demand for additional hostages from Bessho Nagaharu. The 'armed occupation of Mt. Shosha (expulsion of Bessho forces)' that Hideyoshi carried out in retaliation for Nagaharu's breach of contract was the trigger that caused the Kakogawa Conference to collapse and dragged Bessho Nagaharu into a decisive battle with no way out (the siege of Miki Castle).

For readers of no+e, especially history enthusiasts, visiting the currently serene and beautiful Mt. Shosha Engyo-ji must be an immense joy. However, when we walk along the moss-covered approach and look up at the stone walls of the Maniden, we can find there the traces of the raw will and terrifying ingenuity of the Oda-Toyotomi military power, which swallowed a thousand-year world of faith and hacked the space itself for the sake of hegemony.

This content was created based on Gemini and through repeated dialogue with the poster.

• If you have viewed this article, it would be encouraging if you could press the 'Like' button as a memento of your visit to say, 'I saw it!'

• Also, if you liked the content of this article, I would be very happy if you followed the author, as I would like to continue writing such history-related articles.