In the First World War, Kinau was drafted into the German infantry in 1915. He fought in Serbia and Russia and later at Verdun. From 1916 he served in the German Navy, having requested the transfer. He served as a lookout on the light cruiser SMS "Wiesbaden" and died when the ship was sunk in the Battle of Jutland. His body was found on the Swedish shore on the island Väderöbod midsummer's eve 1916 near Fjällbacka. He was later buried on the island of Stensholmen together with other German and British servicemen. He was recognised by carrying a poem, "Letzter Wunsch", which predicted his demise, in a hermetically sealed box in his pocket: