Province of Upper Silesia
Following the Treaty of Versailles after World War I, Kreuzburg was involved in the Upper Silesian referendum in 1921. 95.6% (37,957 votes out of 39,703 participants) voted to remain within Weimar Germany instead of joining the Second Polish Republic. It became part of the Province of Upper Silesia; to differentiate between other places named Kreuzburg, it was known as "Kreuzburg O.S." (referring to "Oberschlesien", or Upper Silesia). By 1939 the town was the seat of Landkreis Kreuzburg O.S. and had 11,693 inhabitants. After the Nazi Party took power in Germany in the 1930s, anti-Polish and anti-Jewish sentiments became more visible. In 1936, the Germans changed the Polish-sounding street names, and in 1938, during the "Kristallnacht" they burned down the synagogue, built in 1886. During World War II, in 1939, the Germans established the Oflag VIII A prisoner of war camp in the city, and in 1943 they transformed it into the Ilag VIII/Z camp for interned citizens of the United Kingdom and the United States. The Germans evacuated the populace before the advancing Soviet army in January 1945.