
Letter from Königstein, Taunus to Dr. Karl Hagemann, January 1916 (friend and patron in Leverkusen and collector of his art); as quoted in the biography-pdf http://www.kirchnermuseum.ch/data/media/downloads/Biography.pdf of the Kirchner museum, Davos
Kirchner suffered then a serious mental breakdown and was also afraid for being drafted once more in the German army, so back in the war
1916 - 1919