Tachikawa Airfield & Army Air Arsenal

Tachikawa Airfield (立川飛行場) and the adjacent Tachikawa Army Air Arsenal (立川陸軍航空工廠) formed the heart of the Imperial Japanese Army's aviation industrial complex in western Tokyo, spanning the cities of Tachikawa and Akishima.

Origins and Development (1922–1937)

The airfield was established in 1922 as a core base for the air defense of the capital, when the Army's 5th Air Battalion (航空第五大隊, soon renamed the 5th Flying Battalion), formed the previous year at Kakamigahara, Gifu Prefecture, and equipped with Salmson 2A2 reconnaissance biplanes, moved in. The site was selected for its proximity to central Tokyo, favorable rail connections via the Chuo Line for fuel and personnel transport, and the vast open terrain of farmland and woodland north of Tachikawa Station.

Initially, Tachikawa served dual military-civilian purposes. On April 1, 1929, when Japan Air Transport (日本航空輸送) launched scheduled domestic air services, Tachikawa was designated as 'Tokyo Airfield' (東京飛行場). However, in 1933, all civilian operations transferred to the newly opened Haneda Airfield, and Tachikawa became exclusively an Army installation.

In November 1924, the Ishikawajima Aircraft Manufacturing Company (石川島飛行機) was founded, relocating to Tachikawa by 1930. In 1936, at the direction of the Army Ministry, the company was renamed Tachikawa Aircraft Company Ltd. (立川飛行機株式会社), with the Imperial Japanese Army acquiring a controlling interest through the Mitsui zaibatsu.

The Army Aviation Complex (1937–1945)

By the late 1930s, Tachikawa had evolved into a sprawling military-industrial aviation complex. The key components included:

Tachikawa Aircraft Company (立川飛行機): Japan's fourth-largest aircraft manufacturer, employing thousands of workers. The company produced over 6,000 aircraft during the war, including its own designs such as the Ki-9 Type 95 trainer (nicknamed 'Akatonbo' or 'Red Dragonfly' for its orange paint), the Ki-36 Army Type 98 Direct Co-operation Reconnaissance Aircraft (九八式直接協同偵察機), and the Ki-55 Army Type 99 Advanced Trainer (九九式高等練習機). Tachikawa also conducted large-scale production transfer (移管生産) of the Nakajima Ki-43 Hayabusa (一式戦闘機「隼」), one of the Army's most important fighters.

Army Air Arsenal (陸軍航空工廠): Formally established on April 1, 1940 in the Akishima area with over 10,000 employees, this was the Army's sole dedicated aviation manufacturing arsenal. It was responsible for aircraft engine production, aircraft design, prototyping, and the manufacture of aviation instruments and components.

Army Air Technical Research Institute (陸軍航空技術研究所 / Koku Gijutsu Kenkyujo): The technical department of Army Air Headquarters moved to Tachikawa in 1928 and became an independent research institute in 1935, conducting aeronautical research, development, and testing. During the Pacific War its successor organization, the Army Air Examination Department (陸軍航空審査部), also evaluated captured Allied aircraft.

In 1939, the Army Aviation Technical School (陸軍航空技術学校) transferred to Tachikawa, further consolidating the site's role as the nerve center of Army aviation.

Adjacent to the Tachikawa complex, Hitachi Aircraft (日立航空機) and Showa Aircraft Industry (昭和飛行機工業) also established factories in the vicinity, creating a dense concentration of aviation manufacturing in western Tokyo.

Air Raids and Destruction (1945)

From February 16, 1945, the Tachikawa complex became a priority target for Allied strategic bombing. The area suffered 13 separate air raids:

• February 16–17, 1945: US Navy Task Force 58 carrier-based aircraft attacked airfields and aircraft factories across the Tokyo region, including Tachikawa.
• April 1945: On April 24, 131 B-29 Superfortresses of the XXI Bomber Command specifically targeted the Tachikawa aircraft engine factory at Yamato, destroying much of the production capacity.
• March–April 1945: Major firebombing raids severely damaged the Tachikawa Aircraft main factory (立川飛行機立川工場).
• June 1945: Further B-29 raids rendered most of the airfield and remaining manufacturing facilities unserviceable.

The Shintentai (震天制空隊), a specialized anti-aircraft ramming unit, was deployed to defend the airfield, but could not prevent the progressive destruction. By the time American forces arrived on September 5, 1945, most structures, hangars, and support facilities had been devastated.

US Occupation: Tachikawa Air Base (1945–1977)

US Army Air Forces elements occupied the base in September 1945. Tachikawa Air Base became a critical logistics and airlift hub for American military operations in the Pacific, particularly during the Korean War and the Vietnam War era. At its peak in the late 1960s, the base housed over 9,000 US airmen and their families.

The base's history was marked by the Sunagawa Struggle (砂川闘争) of 1955–1957, when local farmers and anti-base activists fiercely opposed planned runway extensions. The prolonged resistance, combined with broader political opposition to American military presence and fears of nuclear weapons transport through the base, contributed to the decision to halt expansion and ultimately close the facility. In November 1977, the United States military returned Tachikawa Air Base to Japan.

Transformation: Showa Commemorative National Government Park (1983–Present)

Following reversion, the Japanese government designated the western portion of the former base for development as a national park commemorating the 50th anniversary of Emperor Hirohito's accession to the throne. The Showa Commemorative National Government Park (国営昭和記念公園) opened on October 26, 1983, covering approximately 180 hectares (444 acres). The park features extensive gardens, a large pond, cycling paths, sports facilities, and seasonal flower displays that attract roughly 4 million visitors annually (4.04 million in fiscal 2016).

The eastern portion of the former base now serves as the Japan Ground Self-Defense Force Camp Tachikawa (陸上自衛隊立川駐屯地), housing the Eastern Army Aviation Group. The Tachikawa Garrison Museum preserves some historical artifacts from the site's military past. Several remnants of the wartime era survive, including a water tower from the original Tachikawa Aircraft Company factory.