During the German invasion of Poland, which started World War II, on September 9, 1939, Łańcut was a place of fierce defense by Poles under the command of Colonel Stanisław Maczek, who would become one of the Polish heroes of World War II. During the subsequent German occupation, the "Einsatzgruppe I" entered the town between September 17 and October 5, 1939 to commit various atrocities against Poles. In November 1939, the Germans deceitfully requested the presence of Polish intelligentsia from the town and county at a supposed conference on the county's economic matters, at which they then arrested over 200 people, including local officials, teachers and priests (see "Intelligenzaktion"). Some of them were imprisoned in Rzeszów along with Poles from other towns of the region. A temporary prisoner-of-war camp for Polish soldiers was operated in Łańcut in 1939, and around 25,000 people were held there in mid-November 1939. From 1942 onwards the German occupiers began transportation and murder of the Jewish community; very few of the community survived. There is a well-known case where a Jewish family from Łańcut was hidden from the Germans by the Polish Ulma family in the nearby village of Markowa. In 1944 the Germans discovered the hideout and murdered the Polish family and two hidden Jewish families, 16 people in total, including children. The town's architecture avoided significant damage during the war.