Construction of the Yura Fortress Tomogashima Battery Group

The Kitan Strait, between Awaji Island and the Kii Peninsula, is the gateway from the Pacific through the Kii Channel into Osaka Bay. Under its policy of static national defence, the Meiji government decided to fortify both shores and the Tomogashima islands in mid-strait in order to protect Osaka and Kobe. Work on the Yura Fortress began in March 1889 with a battery in the Yura district of Awaji; the Yura Fortress Command was set up in July 1896, and in May 1903 the Naruto Fortress was merged into it, creating a coordinated system covering the Yura (Awaji), Tomogashima, Kada-Miyama (Wakayama coast) and Naruto districts.

Tomogashima, in the middle of the strait, formed the central defensive group. Over about sixteen years from 1890 the Imperial Japanese Army built five batteries (Nos. 1 to 5) on Okinoshima island and a redoubt on Torajima, with military roads, piers, a power station and searchlight positions. No. 3 Battery, near the highest point of the island, was the main work, armed with eight 28 cm howitzers and provided with brick underground magazines and shelters; Wakayama tourism material dates its completion to 1890. Nos. 1 and 2 Batteries, facing the western side of the strait, each mounted four 27 cm guns, and No. 2 was completed in 1898. The earlier text on this site also lists 12 cm guns, shell hoists and communication tunnels and a peak garrison of about 600 soldiers. The island was classified as a restricted military zone and removed from civilian maps in 1888, and after the Fortified Zones Law of 1899 entry, photography and sketching in the area were restricted.

The Yura Fortress never saw action. Once aircraft had become the main arm, its batteries had almost no role in the Second World War; American forces disarmed the fortress after the surrender, and No. 2 Battery on Tomogashima was blown up at the end of the war, while the other works survive in comparatively good condition.

After the war Tomogashima was included in the Setonaikai National Park and opened to the public. The battery group, with No. 3 Battery foremost, was selected as a Civil Engineering Heritage site by the Japan Society of Civil Engineers in 2003, and the brick magazines and gun pits are now a well-known war relic and visitor attraction of the Kada district of Wakayama City, reached by boat from Kada port.