After 1320, the city appeared in writing as "Dorpmunde".In the years leading up to 1344, the English King even borrowed money from well-heeled Dortmund merchant families Berswordt and Klepping, offering the regal crown as security.
During the industrialisation of Prussia, Dortmund became a major centre for coal and steel.
Bombing targets of the Oil Campaign of World War II in Dortmund included Hoesch-Westfalenhütte AG, the "Hoesch-Benzin Gmb H" synthetic oil plant, and the Zeche Hansa.
The devastating bombing raids of the 12th March 1945 with 1,108 aircraft (748 Lancasters, 292 Halifaxes, 68 Mosquitos) destroyed 98% of buildings in the inner city center and 4,851 tonnes of bombs were dropped through Dortmund city centre and the south of the city; this was a record to a single target in the whole of World war II.
The US 95th Infantry Division, attacked the city on 12 April 1945 against a spirited German defense.
The division, assisted by close air support, advanced through the ruins in urban combat and completed its capture on 13 April 1945.