Kokura Arsenal Ruins

The Kokura Army Arsenal (小倉陸軍造兵廠, Kokura Rikugun Zōheishō) was established in 1916 as the Kokura Arms Factory, one of six state-owned arsenals under the Imperial Japanese Army. Located in the former city of Kokura (now Kokurakita Ward, Kitakyushu), the facility occupied approximately 583,000 square meters with an east-west span of 735 meters and a north-south span of 1,325 meters.

Following the Great Kanto Earthquake of 1923, which damaged the Tokyo Arsenal, it was decided in 1927 to consolidate and relocate its operations to Kokura, and the new arsenal was completed in October 1933. At its wartime peak in 1943, the arsenal encompassed roughly 300 buildings and employed approximately 40,000 workers, including mobilized students. The facility was divided into three production districts: the first district (near present-day Daimon 1-chome) manufactured light tanks and military vehicles; the second district (near Kanda 1-chome) produced machine guns, rifles (including the Type 38 and Type 99 Arisaka), and small arms; the third district along the Shirakawa River manufactured artillery shells and high-caliber anti-aircraft guns. Chemical weapons were also reportedly produced on site.

Allied intelligence identified the Kokura Arsenal as the largest producer of artillery, military vehicles, and small-arms ammunition in southern Japan, making it a prime strategic target. On August 6, 1945, the arsenal was designated as the backup aiming point for the Little Boy uranium bomb that struck Hiroshima. Three days later, on August 9, Major Charles W. Sweeney piloted the B-29 Bockscar from Tinian with the Fat Man plutonium implosion bomb, with Kokura Arsenal as the primary target.

Bockscar arrived over Kokura and made three bombing runs, but the bombardier could not visually acquire the aiming point through 7/10 cloud cover compounded by thick smoke drifting from the massive firebombing raid on neighboring Yawata the previous night (August 8). Under orders to bomb visually rather than by radar, and with Japanese anti-aircraft fire and fighters closing in and fuel running critically low, Sweeney diverted to the secondary target — Nagasaki — where Fat Man was released at 11:02 local time.

This twist of fate is often referred to in English as "the Luck of Kokura" or "Kokura's luck," a phrase used to describe unknowingly escaping catastrophe. In Kokura, the saying carries a complex emotional weight: gratitude for survival tempered by awareness that another city suffered in its place.

The arsenal was dismantled after Japan's surrender. The site underwent large-scale redevelopment during the postwar period. Today, the former headquarters area houses the Kitakyushu Central Library (designed by Arata Isozaki, opened 1974), while the broader grounds became Katsuyama Park. In 1976, the city of Nagasaki donated a replica of the Nagasaki Bell, which was installed in the park along with a peace memorial monument and plaque. Annual peace ceremonies are held on August 9. The Kitakyushu City Museum of Peace (北九州市平和のまちミュージアム) opened in April 2022 to preserve and transmit the memory of the war.