In response, they built a huge network of shore fortifications throughout the rest of the 600s, often with the assistance of Baekje engineers, generals and artisans.

Unaware of the outbreak of the Silla-Tang War (670–676), the Japanese would continue to build fortifications until 701, after finding out that Silla was no longer friendly with Tang.

[2] The Einōsan Castle is one such fortification, and was situated at the eastern base of the Takanawa Peninsula, facing the Geiyo Islands in the Seto Inland Sea.

The site overlooks the Kurushima Straits on two independent mountain massifs, Einōsan and neighboring 132-meter Iyōzan.

[3] The site is about 10 minutes by car from Iyo-Miyoshi Station on the JR Shikoku Yosan Line.