The German leader responsible for initiating World War II was Adolf Hitler, who came to power as Chancellor of Germany in 1933 and led the National Socialist German Workers' Party (Nazi Party). Hitler's aggressive expansionist policies aimed at re-establishing Germany's power included the annexation of Austria and the invasion of Poland in 1939, which directly triggered the war. His ideology was marked by extreme nationalism, militarism, and anti-Semitism, leading to the outbreak of conflict across Europe. Hitler's leadership would result in devastating consequences, including immense loss of life and widespread destruction throughout the continent and beyond.