During the Russo-Japanese War of 1904–1905, Japanese forces landed at Chongjin and established a supply base due to its proximity to the front lines in Manchuria. The Japanese remained after the end of the war, and in 1908, declared the city an open trading port both for the transport of Korean resources and as a stopping point for resources from China. The city was known during this period as “Seishin”, after the Japanese pronunciation of the Chinese characters for its name. The Imperial Japanese Army’s 19th Division was headquartered in Ranam from 1918, where the Japanese built a new planned city based on a rectangular street grid. In 1930, Nippon Steel built a large steel mill, the Seishin Iron and Steel Works, in the town. Ranam was annexed to Chongjin in 1940, which was elevated to city status. The city was overrun after a brief resistance by the Soviet Union on 13 August 1945, only two days before the end of World War II.