War II and the establishment of Czechoslovakia. Olomouc annexed two neighbouring towns and 11 surrounding villages, gaining new space for additional growth and development.
Serious tensions arose between ethnic Czechs and Germans during both world wars. During WWII, most of the town's ethnic German residents sided with the Nazis; the German-run town council renamed the main square after Adolf Hitler. World War II brought a rise in anti-semitism and attacks on the Jews that reflected what was happening in Germany. On Kristallnacht (10 November 1938), townspeople destroyed the synagogue. In March 1939, city police arrested 800 Jewish men, and had some deported to the Dachau concentration camp. During 1942–1943, ethnic Germans sent the remaining Jews to The resienstadt and other German concentration camps in occupied Poland. Fewer than 300 of the town's Jews survived the Holocaust.
After Olomouc was liberated, Czech residents took back the original name of the town square. When the retreating German army passed through the city in the final weeks of the war, they shot at its 15th c. astronomical clock, leaving only a few pieces intact (these are held in the local museum). In the 1950s, the clock was reconstructed under the Soviet government; it features a procession of proletarians rather than saints. After the war, the Communist government participated in the expulsion of ethnic Germans from the country, as happened throughout eastern Europe, although many of these people had lived for two centuries in the region.
Despite its considerable charms, Olomouc has not been discovered by tourists in the same way that Prague, Český Krumlov and Karlovy Vary have. Its inner city is the second-largest historical monuments preserve in the country, after Prague
