Final answer:
Hitler traveled to Vienna as a young man to join the Academy of Fine Arts, was rejected, and then became involved in extremist politics, which shaped his future ideological path. He later became the leader of the National Socialist German Workers Party and wrote 'Mein Kampf' in prison after the failed Beer Hall Putsch.
Step-by-step explanation:
When Hitler was 18, he traveled to Vienna to enter the Academy of Fine Arts, dreaming of becoming an artist. Despite his later claims of conspiracy against his talents, he was rejected due to a lack of artistic skill, as evidenced by his surviving works.
This rejection created a turning point in Hitler's life, as he became increasingly involved in extremist politics while living in Vienna, brewing his virulent anti-Semitism and forming the early foundations of his future ideology. He later moved to Germany and volunteered for the German army during World War I, a period that further shaped his radical views.
After the war, he joined the National Socialist German Workers Party, eventually becoming its leader, and adopted the swastika symbol for the party's flag. Hitler used his time in prison after the failed Beer Hall Putsch to write Mein Kampf, outlining his vision for Germany's future, which notably included uniting all German-speaking peoples and searching for Lebensraum.