Trenches

Trenches / 空堀

This is a subtype of Features

The term karabori Trenches in general covers a wide range of trench like fortifications around castles and may also be called trenches, ditches, empty moats, or dry moats in English. Karabori are dug to prevent attackers from easily entering or moving around a castle. There are also various subtypes depending on the location in the castle and orientation such as horizontal, vertical or across a mountain ridge. There are also subtypes depending on structure like unebori and shouji-bori. In flatland castles they are often similar in structure to water moats but without the water. Both water moats or dry trenches have their own unique advantages and disadvantages. For example, it can be harder for intruders to hide in a dry moat and there no natural water sounds that might disguise entry. The slick clay sides of many castles in the Kanto region were especially slippery and difficult to climb. I have had a difficult time even in hiking boots getting up only slight slope where there is no grass for traction. On the other hand, water moats, where feasible, can be a good psychological deterrent. Attackers don't know how deep they are or what is underneath. A wet intruder will likely leave a trail and they will need to expend more energy to get across.

When you see photos or visit these locations yourself you may think that these trenches are shallow and would not be much of a deterrent but keep in mind that they have filled with leaves and dirt and have been eroded significantly over the last 400 years. What is now a meter or less deep may have been two or three times that deep at one time.

Some terms related to trenches that you may see include:

Horikiri (堀切)

This is a deep trench cut across a mountain ridge to impede attackers from easily climbing the ridge. You see a lot of these on the path to mountaintop castles and it's usually the first sign that you've entered a castle. Unless there are signs to point them out or you are familiar with seeing horikiri you might not notice them at all. But, if you think about it, such a sudden steep dip in a ridge is very unnatural.

Yokobori (横堀)

A horizontal trench across a slope or mountain. It can also provide an easier route for defenders to cross a slope.

Tatebori (竪堀)

A vertical trench running down a slope. It can be used to impede attackers from easily crossing a slope and can force them into a kill zone.

Unejotatebori (畝状竪堀)

Several parallel tatebori across one slope on a mountaintop castle. They may be difficult to see if the are on a steep side of the castle that you cannot get to.

Shojibori (障子堀)

A wider trench with square depressions carved out. It forces attackers to either walk the narrow ridges and be easily fired upon or scale up and down the slick clay walls putting them in vulnerable positions and using a lot of physical energy. These are often attributed to the Hojo but the Hideyoshi's Osaka Castle had great shojibori too. Unfortunately you can not longer see them. The only really good shojibori you can see today are at Yamanaka Castle in Shizuoka but many more have been excavated and reburied over the years.

Unebori (畝堀)

A trench with ridges across them. This is similar in design to the shojibori but instead of a "waffle" like design it is only a single row of dugout depressions.

Empty Moats (空堀)

These are the moats you are more likely to see at flatland castles. They are similar in size and shape to water moats but without the water.

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Castles with Trenches

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