During the early stages of World War II and the Poland Campaign, Katowice was essentially abandoned by the Polish Army, which had to position itself around Kraków. Nevertheless, the city was defended by local Poles, and the invading Germans immediately carried out massacres of captured Polish defenders. In the following weeks the German "Einsatzkommando 1" was stationed in the city, and its units were responsible for many crimes against Poles committed in the region. Under German occupation many of the city's historical and iconic monuments were destroyed, most notably the Great Katowice Synagogue, which was burned to the ground on 4 September 1939. This was followed by the alteration of street names and the introduction of strict rules. Additionally, the use of Polish in public conversations was banned. The German administration was also infamous for organising public executions of civilians and by the middle of 1941, most of the Polish and Jewish population was expelled. The Germans established and operated a Nazi prison in the city, and multiple forced labour camps within present-day city limits, including two camps solely for Poles ("Polenlager"), four camps solely for Jews, two subcamps (E734, E750) of the &lt;a href="Stalag%20VIII-B"&gt;Stalag VIII-B/344&lt;/a&gt; prisoner-of-war camp, and a subcamp of the Auschwitz concentration camp. Eventually, Katowice was liberated by the Red Army in January 1945. Significant parts of the downtown and inner suburbs were demolished during the occupation. This, however, cannot be compared with Warsaw, where the level of destruction reached 85%. As a result, the authorities were able to preserve the central district in its prewar character.