A Layout that Embodies War Tactics
Akō Castle was designed based on Kōshū-ryū war tactics. This diagram shows the basic principles of these tactics. This is a model of how enemies launching a frontal assault can be attacked from the side (yokoya) by arranging the stone walls creatively.
The Castle that Mastered “Yokoya”
Generally, castles from the modern period created defensive “yokoya” structures, which allowed castle forces to attack enemies from multiple directions, by creatively laying out the stone walls. Akō Castle is the epitome of this strategy. The black arrows point to structures seen in standard castles, and the red arrows point to structures unique to Akō Castle that provided multi-layered “yokoya.” Akō Castle is the only place in Japan where some of these stone wall configurations exist.
The Stone Walls of the Sannomaru’s Shioyamon Gate
These unique walls use a combination of acute and obtuse angles to create structures that allowed castle guards to attack enemies from the side when they crossed the wooden bridge in front of Shioyamon Gate.
Arrow-Slits
These holes were used to shoot arrows or bullets at incoming enemies from behind the trenches. The rectangular holes were for arrows, and the triangular and circular holes were for bullets.
The Yokoya East of Honmarumon Gate
A structure built to attack enemies from the side when they crossed the earth-paved bridge in front of the gate.
The Sannomaru’s Yokoya Byōbu-Ore
A special stone wall that jutted out to allow for attacks from both sides of a long pathway.
Curved Stone Walls and Mizuhineri Indents
The stone walls are constructed with curves and angles, reinforcing castle defences against enemies that approach the gate.