Edo Castle Stone Quarries
The Stone quarries and Kokuin of Edo Castle
Everyone, well most Jcastle geeks that is, have marvelled at the immense stone walls of castles like Edo-jo, Osaka-jo, and Nagoya-jo. But, have you ever really thought about how they were built? Where did all that stone come from? It wasn't in the riverways of Edo. Who actually built those walls? Stone pilings were used to prevent erosion and to strengthen earthen embankments for a long time. Big stone walls were built by Nobunaga and Hideyoshi, but the Tokugawa took that to a whole new level building bigger and more vast walls than had ever been attempted before. Big keeps, beautiful gates and towers (yagura) may be magnificent to behold, but the strength of any one castle really comes down to it's network of moats and stone walls.
Tenkabushin (天下普請) After years of war and strife an unstable peace was brought to Japan with the founding of the Tokugawa Bakufu. In order to maintain that peace (and their control) the Tokugawa kept all regional daimyo too busy to war with a series of infrastructure projects called Tenkabushin. Constructing castles for the Tokugawa was the most famous example, but there were also a number of other projects around the country to improve roads, river ways and some important temples and shrines. We call it "tenkabushin" today, perhaps to emphasize the role in the Tokugawa's master plan to control all Japan (tenka), but at the time they were simple called 公儀御普請 or "public infrastructure projects".
1635 starts sankin kotai.
The castles built under this umbrella are listed below:
Edo Castle Nagoya Castle Sunpu Castle Takada Castle
Osaka Castle Iga Ueno Castle Kano Castle Fukui Castle Hikone Castle Zeze Castle Nijo Castle Tanba Kameyama Castle Sasayama Castle
If you consider this a network of castles controlled by the Tokugawa, it's also a giant wall of defensive structures around central Japan (with a few exceptions for Tokugawa strongholds in the East). The role of these castles was to prevent the western daimyo who were defeated at the Battle of Sekigahara from rebelling or making any major incursions into the rest of Japan and Tokugawa held territories.
Many of the Tenkabushin castles listed above are also famous for their impressive and extensive stone walls. The rest of this article describes the building of stone walls for Edo Castle, but parts of the story are applicable to many others, particularly Nagoya Castle, Osaka Castle, Sasayama Castle, and Sunpu Castle.
Stones for Edo Castle
Look at the two photos below. The one on the left is a stone wall from Edo Castle, the one on the right is Osaka Castle. The color difference is due to the type of stone. The darker stones of Edo Castle are called anzangan 安山岩 (andesite) those on the right are kakogan - 花崗岩 (granite). The type of stone used in the walls can tell you about the origin of the stone. The andesite stone for Edo Castle comes from the Izu Peninsula. Occassionally you see a few nice big white stones, mainly used as corner stones, at Edo Castle too.
Look at the photo below. Notice the white stones on the corner compared to the darker stones behind. While walking around Edo Castle, I've mistakenly heard people think the white stones must be "concrete" to replace ones that were broken or missing. Actually, the white looking stones are simply a different type of stone called kakogan (granite) as opposed to the darker ones which are andesite (anzangan). The second photo shows Osaka Castle which uses much more granite because it is more readily available around the Osaka area. IN the case of Edo Castle, the granite blocks are used on the corners because they are marginally harder than the andesite. Andesite has a wider variety of differing characteristics which make it possible to identify the place it came from. The granite, on the other hand, is harder to identify precisely where it came from. To this day, we have some ideas where the granite for Edo castle may have come from based on the proximity granite locations to Edo , but the andesite, which makes up the vast majority of stone at Edo Castle, is mostly from the Izu Peninsula.
Stone Wall Construction at Edo Castle
The construction of Edo Castles magnificent walls began in 1604 and lasted through three Tokugawa Shoguns (Ieyasu, Hidetada, Iemitsu).
The Tokugawa utilized most of the daimyo to some extent to build the stone walls of Edo Castle. The Western Daimyo tended to get the more labor intensive and more expensive jobs while allies got lighter duties. In the photo below you see an example diagram of a section of stone wall at Edo castle and how it is divided among several daimyo for construction. This is actually a XX period construction in 3rd round of wall building.
Assignments were split into two major types:
Moat Construction (堀方): Typically, the Eastern daimyo were responsible for digging the trenches, moats and creating the foundation for stone walls.
Stone Wall Construction (石垣方 ishigakikata): Typically the Western Daimyo, were responsible for quarrying the stone and building the walls. Under the third Shogun Hidetada, this was further broken down to those responsible for stone quarrying (寄方) and those building the walls （築方）
Ishigakikata daimyo were assigned to areas of Izu to quarry the stone, but had to find and lay claim to their specific quarry within. The stone was cut, partially shaped and then transported to ports along the coast. The stone was shipped from these ports on boats by sea to Edo. Once they arrived in Edo, the stone was offloaded at ports and again transported overland to each daimyo's stockpile which was sometimes their own Edo residences. In fact, daimyo in charge of gathering stone were not allowed to work on building their own residences until they filled their quotas. Throughout this chain of stone logistics, the daimyo themselves were responsible for acquiring (building, buying or borrowing) the ports, ships, and locations to stockpile their stone.
The first round of stone wall construction at Edo Castle lasted from about 1604-1606 involving 28 of the Western daimyo. In just over 2 years, the first walls of the Honmaru, Ninomaru, and Sannomaru were completed. Some of these well-known daimyo; including Kato Kiyomasa (Kumamoto), Maeda Toshimitsu (Kanazawa), Mori Hidenari (Hagi), Ikeda terumasa (Himeji), Horio Yoshiharu (Matsue), Fukushima Masanori (Hiroshima), got very good at building huge stone walls in a short time and went on to build their own impressive castles in the same manner.
- The kokuin you see all over Kanazawa castle are a result of the Maeda taking in the same manner of construction employed by the Tokugawa to build their own walls. The divided the work among their retainers who were responsible for cutting stone and building the walls.
At the peak of Edo castle wall construction, 3000 boats per day were making the trip twice a month. It may have been easier than transporting stone over land, but it was by no means safe. Many boats sunk in the process and to this day you can still see stones that were bound for Edo Castle on the bottom of the sea.
The second photo illustrates loading large cornerstones onto a boat. Only 2 of these large stones could be loaded on a single boat. The large cornerstones are also known as "100 Man Stones" (百人持ち石) because it took a 100 men to move it.
In the following photos you can see a map of Izu with some of the main quarry areas highlighted with Orange dots. This is only a small number of the bigger quarries, much of the coast had quarries or ports along it. The lines also indicate the route to Edo from the quarries along the coast.
PICTURE map
PICTURE boat
Kokuin - Daimyo sigils
Each daimyo who was assigned to quarry stone was also given a quota based on the size of their domain. As the stones were cut and prepared for shipping to Edo, the stones were marked with the daimyo's sigil so that when it arrived in Edo the officials could tabulate how much stone was provided and make sure the daimyo were meeting their quotas. The sigils also served to prevent other daimyo from stealing previously cut stones or laying claim to another daimyo's stone at the ports. Quarrying such stone is hard dangerous work. Even if it wasn't sanctioned by the daimyo, it is possible that the workers may have laid claim to another daimyo's stone given the opportunity. I read in one account of the Hokkawa Quarry that there were so many injuries that the stream through the quarry was often tinged red with blood.
Markings on the stones of stone walls are often lumped into one category called kokuin, but not all kokuin are created equal. The most common are daimyo sigils or some simplification of the sigil. You may also see a slight alteration to the sigil or an additional marking on the same stone which indicates a certain retainer of the daimyo or a quarry where it came from.
PHOTO EXAMPLE - bunch of kokuin wall, kato+retainer kokuin
You will also find other markings on stones that were used by the builders during construction of the walls (符丁). The purpose of much of these are not known today but some of the numbers may be guessed. There are also stones with words on them and should probably be called kokumon (刻文).
PICTURE kokufu / kagi / numbers PICTURE kokumon / hirakawamon
(Footnote)
Unfortunately, it is not always easy to connect a kokuin to a specific daimyo. The same marks were used by different daimyo in different areas and times. Sometimes the mark used was actually that of a retainer in charge of the quarry, a stone artisan working the quarry, a mark specific to that quarry. The daimyo's mark may not be related to the kamon (family crest) or other marks such as umajirushi or funajirushi used by the daimyo. The best way to connect a daimyo to a kokuin or specific quarry is actually through historical accounts.
Daimyo used various methods to lay claim to and mark the boundary of their own quarries. Here you see some examples.
PICTURE usami
羽柴越中守石場（細川忠興） はしばえっちゅうのかみいしば
PICTURE heda
PICTURE kato
Back at the castle, you can see kokuin all over Edo Castle if you know where to look. The first thing to note is that not every stone will have a kokuin. Some have been erased by time and weathering, some were simply not on the outside face of the stone, and some stones were also reshaped on site. Futher, kokuin were intentionally erased from areas of high visibility. You would not want to show favoritism to any one daimyo, especially a tozama daimyo, by prominently displaying his mark for all to see. For that reason, the best places to see kokuin are actually using a zoom lens to look across the moats. There are also places where the kokuin were hidden by walls and buildings that no longer exist making them more visible.
At Edo Castle, kokuin tend to be mixed up. There are some areas where you tend to see a lot of the same marks, but rarely do you find a spot that is exclusively one mark. This is something you will see more often at Osaka Castle where the quarrying and building of sections of the stone walls was done by the same daimyo. As mentioned earlier, the walls built under Hidetada as well as repairs and changing of some of the walls at Edo Castle over time led to the kokuin being more generally mixed together. In a few places you can find a section of wall where there is a clear break between one daimyo and another. The below borders are from Edo Castle and Osaka Castle. The Edo Castle one in particular is interesting. We know that the stone walls behind the honmaru around the Kitahnebashi Gate were some of the earlier walls built at Edo Castle so I would surmise that this spot was both quarried and built by the respective daimyo.
A final use for kokuin that may sometimes be seen at castles is a mark on the top side of the top stone of a wall. This was also intended to delineate the border between sections of responsibility for wall construction. Unfortuately, you can rarely walk along the top of a wall to see whether there are marks or not! The below photo is of one at Edo Castle. I think I have photos of a couple at Nagoya-jo and Osaka-jo too but have not dug them out yet.
PHOTO tenpanishi at hibiya park (2014 photos)
white corner stones 2014 kitahanebashi
Stone Quarries
If you've read this far into this kokuin journey, let's go visit some of the former stone quarries in Izu.
Several years ago, I befriended a retired expert who had a special interested in the stone quarries of Izu and helped to get some documented and protected. I joined him on some travels to survey and/or re-visit some of these sites as well. A few of these photos were posted to Facebook at the time, but most are seeing the light of day for the first time. The photos are also GPS tagged and I'm providing maps of these photos and quarries for reference purposes only. They are mostly on private land and, as I understand it, some of the owners do not appreciate people walking around their woods without permission. Ito City has taken some steps to make a bit of tourism out of these stone quarries around the Usami area. They have developed some hiking trails and maps to get to the sites. I have not visited them in some years myself so if anyone is interested in a trip to Usami I'd be happy to go along, just make sure it is before Golden Week as the foliage and weeds will start making it difficult to see much.
Exploring these ruins is actually great fun. You can really imagine them being an active quarry site. There are stone sin all stages of being cut and formed, including mistakes or incorrectly split stones! You will see many leftover stones with kokuin that were never carried off to Edo. There are "leavings" (as I call them) which are the leftover bits carved off a stone and have many ya-ana (arrow holes). There are stones with the outline of a ya-ana for later carving and dotted lines along which a stone is expected to be split. Most of these sites have no trails so it's up to you to explore and check each side of a stone and sometimes clean them off to see if there is anything under the fallen leaves or weeds. You could probably spend a full day at any one of these sites. Explore my photos of these sites below to see what you might find too !
Author's note: I started this article over 4 years ago and have stopped and started several times since, not really sure what I wanted to do with it. It started with all the little places around town where you can find remains of these stone walls, which morphed into a showcase of interesting spots and trivia about the stone walls, which somehow led to a feature about kokuin. But, I can't talk about kokuin without talking about "why" the stones were marked. That leads to tenkabushin and stone quarries. If the article seems a little disjointed, that's why. Perhaps I'll delve into one of these other topics next, but for now, here is the (hopefully) first article in a series about Edo Castle Stone Walls.
