In 1915, soon after the outbreak of World War I, the hotel was commandeered by the High Command of Coastal Defence. Haerlin’s three sons were drafted. Two, Otto and Wilhelm, died at the front in Flanders while his third son, Fritz, survived the war. During the German Revolution of 1918–1919, mutinous sailors shelled the hotel from the nearby Alsterpavillon. The revolutionary Supreme Marine Council took over the hotel from November 1918-March 1919. The looted and damaged hotel had to be completely renovated. In 1919 the hotel opened the Haerlin Restaurant, followed by the Art Deco styled Jahreszeiten Grill in 1925.