Kasumigaura Naval Air Group

The Kasumigaura Naval Air Group (霞ヶ浦海軍航空隊, Kasumigaura Kaigun Kokutai) was the Imperial Japanese Navy's most important land-based aviation training facility and the birthplace of Japanese naval aviation. Situated on the western shore of Lake Kasumigaura in what is now Ami Town, Inashiki District, Ibaraki Prefecture, the base was ideally located for both land-based and seaplane training operations, with the vast lake providing a natural runway for floatplanes and flying boats.

The origins of the base date to 1917, when Commander Kaneko Yōzō (金子養三) returned from a European inspection tour convinced that naval aviation needed dedicated land airfields beyond existing seaplane stations. The Ami area was selected for its flat terrain, proximity to Tokyo, and the availability of Lake Kasumigaura for waterborne aircraft operations. Construction began in 1920, and the Kasumigaura Airfield was officially opened on July 22, 1921. The following year, on November 1, 1922, the Kasumigaura Naval Air Group was formally established as the Imperial Japanese Navy's third air corps.

A pivotal event in the base's early history was the Sempill Mission (1921–1922), a British aviation advisory mission led by Captain William Forbes-Sempill that trained Japanese naval aviators in modern techniques at Kasumigaura. The mission transferred critical aviation technology and training methods that would shape Japanese naval air power for decades. The base quickly gained international prominence: in August 1929, the German airship LZ 127 Graf Zeppelin landed at Kasumigaura during its round-the-world flight, drawing 200,000 spectators. In August 1931, Charles Lindbergh visited the facility. Emperor Showa personally inspected the air group in November 1929.

Throughout the 1930s and into World War II, Kasumigaura served as the navy's premier pilot training center, producing the skilled aviators who would fly in every major Pacific campaign. In 1939, the Naval Flight Preparatory Course (Yokaren, 予科練) program was transferred from Yokosuka to Kasumigaura due to increasing trainee numbers. The following year, the seaplane training section was separated and reorganized as the Tsuchiura Naval Air Group (土浦海軍航空隊), which specialized in Yokaren education. Between 1930 and 1945, approximately 240,000 young men entered the Yokaren program nationwide, of whom roughly 24,000 went to the front; tragically, some 19,000 of these perished in combat, many in special attack (kamikaze) missions.

In February 1945, U.S. Navy carrier aircraft from Task Force 58 attacked Kasumigaura Airfield, causing significant damage. On August 3, 1945, the air group was transferred to the 15th Naval Training Combined Air Fleet shortly before Japan's surrender. After the war, the site was occupied by U.S. forces and subsequently transferred to the Japan Ground Self-Defense Force in 1953. Today the former base area encompasses JGSDF Camp Kasumigaura (a supply depot and helicopter training facility with approximately 2,000 personnel), the Ibaraki University Faculty of Agriculture, Tokyo Medical University Kasumigaura Hospital, and the Yokaren Peace Memorial Museum (予科練平和記念館), which opened in 2010 to honor the memory of the young naval aviator trainees.