Kiel led a rather provincial existence for many years. This changed suddenly, however, when Kiel was made a Prussian naval base in 1865 and then an Imperial War Port in 1871. The navy was soon followed by the docks and the docks by the workers.

Within just a few decades, Kiel had developed into a major city with more than 100,000 inhabitants at the end of the 19th century. By 1918, the population has swollen to 300,000 before falling dramatically thereafter. Hardly any other German city experienced such fluctuations its population as Kiel.

At the end of the First World War, the impulses for revolution in Germany were generated by the Kiel naval mutiny in 1918. This led to the end of the monarchy and the first German democracy, the Weimar Republic.

The city suffered greatly in the aftermath of the war, especially from the far-reaching dismantling of the navy. The economy collapsed almost completely. Later, rearmament under the National Socialists once again resulted in a very one-sided orientation of the city towards military production. As an important mili-tary and munitions site, Kiel was one of the main targets of Allied bombing in the Second World War. After more than 90 air raids, 80 percent of the city was reduced to rubble.