After the Japanese defeat in World War II, the city was under the administration of the Soviet Union, which rented the port from China, until 1950.

In the late 1880s, the German company Krupp was contracted by the Qing dynasty to build a series of fortifications around Port Arthur.

Imperial Japanese Armed Forces war planners, ambitious for control of the Liaodong Peninsula and Port Arthur and also cognizant of that port's strategic position controlling the northern Yellow Sea routes and the passage to Tianjin, were determined to seize it.

[8] Tsar Nicholas II believed this acquisition of a Pacific port would enhance Russian security, and extend its economic influence.

In 1902, the Russian viceroy de-emphasized Dalny, building a palace and cultural edifices at Port Arthur instead.

After the Boxer Rebellion (1900–01) had been extinguished by an international Eight-Nation Alliance of troops, the Imperial Russian Army refused to withdraw its reinforcements from Manchuria and instead began to fortify and garrison the entire route along the Southern Manchurian Railway.

In the end, with over two years of intensive bilateral negotiations having gotten nowhere in clarifying each country's rights, prerogatives, and interests in Manchuria, Japan attacked Port Arthur and the Russian fleet without declaring war in February 1904.

By the end of July 1904, the Japanese army had pushed down the Liaodong peninsula and was at the outer defenses of Port Arthur.

The port eventually fell 2 January 1905 after a long train of battles on land and sea during which the Japanese occupied the whole of the Korean Peninsula, split the Russian Army, devastated the Imperial Russian Navy, and cut off the source of supplies on the railway from Harbin, culminating in the bloody battle known as the Siege of Port Arthur (June–January; some sources place the siege start in late July, a technical difference due to definitions).

After Japan's defeat of Russia, it took over Kwantung Leased Territory and renamed Port Arthur to Ryojun.

Dalian Fisheries University is in the process of moving its English and Japanese language schools to Daheishi, on Lüshun North Road.

From late 2006, Sinorail has operated the Bohai Train Ferry between Lüshun, Dalian, and Yantai, Shandong.