plot shifts between Spain and the Soviet Union. The war also inspired the 1936 poem Til ungdommen, one of his most well-known works, which was set to music in 1952 by Danish composer Otto Mortensen and was performed on numerous occasions (see Til ungdommen). Communism Compassion for the poor and exploited led Grieg to join the Norwegian Communist Party. From 1933 to 1935, he lived in the Soviet Union, where he was officially invited to study the techniques of Soviet stage and film. On returning to Norway, he became an ardent supporter of Joseph Stalin's policies, and became the chairman of the Friends of the Soviet Union (1935–1940). In 1937, he famously wrote a defence of the Moscow Trials, attacking Norwegian authors who had criticized them. His novel Ung må verden ennu være was also a defence of Stalin and the Moscow Trials. In many articles, he criticized the supporters of Leon Trotsky, who lived in Norway from 1937 to 1939. World War II The outbreak of World War II, and especially the German invasion and occupation of Norway, led Grieg to oppose Stalin's policies. In 1939, the Soviet Union signed the Molotov–Ribbentrop Pact with Nazi Germany and, until the 1941 Nazi invasion, instructed Communists worldwide to regard the ongoing war as an "Imperialist" war in which they should not take part. Grieg was a staunch anti-Nazi and Norwegian patriot and committed himself in 1940 to the struggle against the Nazi occupation. In the winter of 1939–40, Grieg served in the Norwegian Army in Finnmark on neutrality guard during the Russo-Finnish Winter War. In 1940, after serving during the Norwegian Campaign against German forces, he escaped to the United Kingdom aboard the same vessel that carried the Norwegian Royal family and the National Gold reserves. War correspondent Once in Britain, Grieg served the Norwegian government in exile, and participated in making patriotic radio programs. He was commissioned in the Norwegian Armed Forces and served as a war correspondent. His work involved visiting and reporting on Norwegian units around Britain. He met Norwegian servicemen on duty in Iceland and other remote outposts. In the summer of 1942 Grieg spent several weeks on the Norwegian island of Jan Mayen in the North Atlantic during which time he wrote the poem Øya i Ishavet. As with other war correspondents, he joined operational missions over occupied Europe. In the course of one of these