Answer
Hubert Pierlot replaced Paul-Henri Spaak as prime minister of Belgium in 1939. He served in this role until 1940, when he was forced to flee to London after the German invasion of Belgium. In London, he served as prime minister in exile and continued to lead the Belgian government until 1944. After the war, Pierlot returned to Belgium and served as prime minister again from 1944 to 1945.