The Shogunate planned to build daiba (a battery) when foreign ships frequently infiltrated Edo Bay at the end of the Edo period.
In 1847, three batteries, Unosaki-daiba, Ashinozaki-daiba, and Owado-daiba, were built on Sarushima.
Currently, only Unosaki-daiba remains, and the other two sites were demolished when the Meiji period battery was constructed.