Denmark has been invaded by Germany several times. Throughout the Middle Ages, Denmark had always been concerned about incursions from its larger and more powerful southern neighbour, Germany. From 1361 to 1370, Denmark was at war with the Hanseatic League, an alliance of powerful, mostly north German, trading towns. During the Thirty Years War (1618-48), the Danish king intervened in support of the Protestants. In response, Jutland was occupied by German Catholics. The final and most famous invasion occurred during the Second World War. In June 1939, Hitler offered a nonaggression pact to adjacent countries feeling threatened by Germany’s expansionist policies including the invasion of Czechoslovakia the preceding years. Denmark was the only neighbour to accept and following the German invasion of Poland, Denmark, like the other Nordic countries, declared neutrality. In 1943 the Danish Resistance – which had around 50,000 members – began armed acts of sabotage. A series of strikes in Summer 1943 were targeted directly at the German occupation. The Danish government refused to introduce the death penalty for sabotage, which would allow the prosecution of the strikers. In response, Germany declared a state of emergency and took direct control. However, on April 9, 1940, German troops took control after only token resistance from the Danish government. Unlike other occupied countries, Denmark remained formally independent, and the government, though under Nazi pressure, had some degree of control. The Danish resistance movement nonetheless continued. Activities included producing illegal newspapers, sabotage, and smuggling fugitives to neutral Sweden. The Danish resistance movement is famous for its protection of virtually all the Jewish people in Denmark, both Danish Jews and refugees from elsewhere. In the fall of 1943, when Germans prepared to round up the nearly 7,000 Jewish people in the country, fewer than 500 were found.