The Water Siege of Oshi Castle

One of the Three Greatest Water Sieges in Samurai History

Samurai castles were not captured easily. They were brought down via force, or by siege leading to attrition of supplies, through trickery and treachery, or even through diplomatic terms. Trickery and treachery however seem to have played the biggest roles.

One of the effective types of castle siege warfare was the water siege. The water siege is a strategy in which a low-lying castle under attack is surrounded by an earthen levee and flooded by damming and diverting river water and torrential rains. It is a fighting method that relies not solely on military force but large-scale civil engineering works. The water siege is an expensive and time-consuming strategy for attackers, but greatly reduces the amount of actual combat, becoming a siege of attrition. Those inside will surrender when food and supplies run out.