A brief on Japanese Fortifications

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A Brief on Japanese Fortifications:

Inspired by Hoel's thread in the Tutorial Forum, I've decided to post this brief on Japanese fortifications. I posted it here, as this will only be a few posts, certainly not the essays in Hoel's thread. I lack the artillery/fortifications training that he has - I am envious of that. I have been to Japan and visited both Himeiji Shiro (Osaka Castle) and Matsue Shiro - a smaller provincial castle held by the local prince or warlord (daimyo) in the western province of Shimaneken, Japan.

The primary difference in Japanese structures versus European structures, is that Japanese structures and castles (shiro) are made of wood, not stone. From a military standpoint, that seems almost silly - just burn the thing down right? In medieval Japan, arson was considered the most serious crime. Those convicted of arson were burned to death.

The reason for using wood instead of stone is due to the fact that the Japanese volcanic island chain frequently suffers earthquakes. If you build a fortification in stone and every 20 years or so there is a major quake. You spend all your time and money rebuilding from a pile of rubble.

Japanese castles, called "shiro" had several different phases in design - the discussion here are for the earlier castles, as later ones were built on flat ground and were more offices of state than defensive structures.

Earlier Japanese castles were built on mottes of rammed earth, man-built hills, similar to motte and bailey structures of early European style. The outside of this foundation/hill was encased in stone. The masons who built these foundations were careful to keep the secret on how they constructed them - often surrounding the entire motte with a fence, so passersby could not see the work being done, or how it was being done.

Unlike many round hill mottes of Europe, the Japanese motte was always square, like the final shape of the fortification to be built upon it.

The castle itself would begin as two heavy and long pieces of timber set at the center of the motte spaced apart so the opening between them would house the central stairway. The placed timbers were the height of the proposed structure. The rest of the castle was built around these two pieces of timber.

Another feature of the castle itself, as one can see from photos of them, are the stack of roof structures used in their construction. Looking at a shiro with a stack of five roof structures might indicate to a viewer that there were five levels to that particular shiro. Not so, this was a ruse, the roof structures are meant to confuse onlookers, often a 5 roofed shiro had 7 or more floors within. The roof structures are there to hide how many floors there actually were. Knowing the number of actual floors could indicate to an attacker how many defenders were within. Often extra floors were hidden behind the various roof structures.

GP

Images below: square motte, motte encased in stone, and Himeiji Castle...