 In the summer of 1917, he became one of the leaders of a movement among sailors in the imperial fleet, whose complaints about food and other conditions soon developed into agitation against the war.He was arrested and condemned to death on 26 August 1917 as a "main ringleader" along with Max Reichpietsch and three other sailors.The sentences on the other three were commuted to penal servitude, but Köbis and Reichpietsch were executed by firing squad on 5 September 1917.