In April 1913 Hartley relocated to Berlin, the capital of the German Empire, where he continued to paint and befriended the painters Wassily Kandinsky and Franz Marc. He also collected Bavarian folk art. His work during this period was a combination of abstraction and German Expressionism, fueled by his personal brand of mysticism. Many of Hartley's Berlin paintings were further inspired by the German military pageantry then on display, though his view of this subject changed after the outbreak of World War I, once war was no longer "a romantic but a real reality". The earliest of his Berlin paintings were shown in the landmark 1913 Armory Show in New York.