Interest in the art of the mentally ill, along with that of children and the makers of "peasant art", was first demonstrated by "Der Blaue Reiter" group: Wassily Kandinsky, Auguste Macke, Franz Marc, Alexej Jawlensky, and others. What the artists perceived in the work of these groups was an expressive power born of their perceived lack of sophistication. Examples of this were reproduced in 1912 in the first and only issue of their publication, "Der Blaue Reiter Almanac". During World War I, Macke was killed at Champagne in 1914 and Marc was killed at Verdun in 1916; the gap left by these deaths was to some extent filled by Paul Klee, who continued to draw inspiration from these 'primitives'.