Yokaichi Airfield & Nunobiki Aircraft Revetments

Yokaichi Airfield (八日市飛行場) traces its origins to Japan's earliest days of aviation. In 1914, civilian aviator Ogita Tsunesaburo conducted a pioneering flight over the Okinogahara plain in what is now Higashiomi City, Shiga Prefecture. Tragically, Ogita died in a flying accident shortly afterward, but his demonstration inspired local officials to petition for an airfield. A civilian airfield — regarded locally as the birthplace of civilian airfields in Japan — was laid out on the site in 1915.

In December 1920, the Imperial Japanese Army established the Aviation 3rd Battalion (航空第3大隊) at the location, and on January 11, 1922, the facility was formally designated as Yokaichi Airfield, making it one of the Army's early airfields. In 1925, the battalion was reorganized and expanded into the Flying 3rd Regiment (飛行第3連隊), with two fighter squadrons and one reconnaissance squadron operating approximately 50 aircraft.

The airfield's military infrastructure occupied a rectangular footprint stretching from Okihara Shrine to the Fudanoji intersection along Route 421. Headquarters, hangars, barracks, and support facilities were clustered along the western side. The Konan Railway extended a branch line to serve the airfield in 1930, underscoring its growing strategic importance.

In 1938, the Flying 3rd Regiment was reorganized into the Flying 3rd Squadron (飛行第3戦隊), becoming a bomber unit; in 1942 the whole unit moved to Toyohara in Karafuto, and the 104th Training Flying Regiment was assigned to Yokaichi in its place. The airfield also housed the Osaka Army Aviation Arsenal's Yokaichi Branch, which handled aircraft maintenance and supply.

A notable wartime occupant was Toshiro Mifune (三船敏郎, 1920–1997) — the internationally celebrated actor who would later star in Akira Kurosawa's masterpieces. Before his film career, Mifune served at Yokaichi Airfield as a private first class (上等兵) on special duty in the 7th Company, where he was in charge of the cookhouse; he is also commonly described as having worked on aerial photographs during his army service.

As the war situation deteriorated and the threat of American air raids intensified, the military began constructing aircraft shelters (掩体壕, entaigo) in the Nunobiki Hills south of the airfield from around 1944. These shelters were designed to protect increasingly scarce aircraft from bombing raids. The Nunobiki Revetment Group (布引掩体群) ultimately comprised 17 shelters of four distinct structural types: reinforced concrete dome structures, wooden arch-beam dome structures, wooden hangar types, and open roofless types. Several remained unfinished when the war ended, indicating the urgency and resource constraints of late-war construction.

In the war's final phase, the 244th Fighter Regiment (飛行第244戦隊) — a distinguished homeland defense unit that had engaged B-29 formations over Tokyo from its base at Chōfu — relocated to Yokaichi Airfield by way of Chiran and Komaki. The 8th Aviation Training Unit, the 254th Airfield Battalion and the 56th Independent Machine Cannon Company were also stationed here. On July 24–25, 1945, American aircraft strafed Yokaichi and attacked the airfield, killing four civilians.

Following Japan's surrender on August 15, 1945, all aircraft at the field were incinerated under occupation directives. The land was redistributed — returned to original owners or allocated as farmland to Japanese repatriates from overseas colonies. Former military buildings were relocated and repurposed as schools and government offices. The distinctive land parcels created by this redistribution remain visible in modern aerial photography.

The Nunobiki Revetment Group was rediscovered and recognized as an archaeological site in 2000 (Heisei 12). Between 2007 and 2009, the Higashiomi City Board of Education conducted comprehensive surveys covering approximately 44,000 square meters, documenting all 17 revetments along with taxiways, three or more smaller shelters, one embankment-like facility, and over ten individual air raid shelters. The complex was designated a buried cultural property (埋蔵文化財) in 2006. Today, the revetments — including two reinforced concrete structures — stretch along a 2-kilometer line at the northern base of the Nunobiki Hills, accessible via forest trails from the Higashiomi City General Sports Park. Some structures show deterioration with partial ceiling collapses, and visitors are cautioned about approaching damaged shelters. Okihara Shrine (沖原神社) at the southwestern corner of the former airfield preserves relocated gate pillars from the airfield's main entrance, while the nearby Heiwabashi (Peace Bridge) spanning the Hebisunagawa River was named to commemorate the community's postwar pledge against war.