Section of Earthen Embankment of the Western Outermost Moat
This wall of rammed earth is a section of the earthen embankment that ran along Matsumoto Castle’s outermost moat. The castle grounds formed a rough trapezoid, with each side facing one of the four cardinal directions. This section of the embankment formed part of the western side. The outermost moat separated the castle compound from the surrounding town, farms, and merchant residences, and it was the castle’s first line of defense.
The earthen embankment was over 3.5 meters tall and topped with a mud-plaster wall between 2.5 and 2.7 meters high. Fourteen watchtowers stood along its length. Travel to and from the castle compound was done through four fortified sally ports (umadashi) and the Ōtemon Gate in the south.
What Is an Earthen Embankment?
Earthen embankments are walls of packed dirt that were commonly used for fortification in the sixteenth century. At Matsumoto Castle, these walls were built along the castle moats as additional defenses. Enemies attempting to reach Matsumoto Castle would have faced the deep water of the moats followed by the sheer slopes of the embankments. Furthermore, any attackers who attempted to cross the moat and make the climb would have been exposed to fire from gunners and archers positioned along the embankment.
How Was the Outermost Earthen Embankment Built?
As workers dug the outermost moat, they piled the excavated earth along the bank. This earthen mound was then shaped into a sloping, flat-topped wall of earth roughly 17.5 meters thick at its base. The resulting embankment ran along the entire 1,940-meter circumference of the outermost moat. Especially for its era, the project would have required a tremendous amount of time and manpower.
Earthen Embankments versus Stone Walls
Earthen embankments had several advantages over stone walls. They could be built using earth taken from the moat, which was readily available, whereas stone had to be gathered, transported, and shaped. Constructing a stone wall required the expertise of masons, but an earthen embankment could be built by unskilled laborers. For these reasons, earthen embankments were much faster to construct and therefore more practical for fortifying a large area quickly. Another advantage of earth over stone was its ability to absorb projectiles. Unlike stone, which can shatter, earthen embankments were better able to withstand gunfire.
