"The central figure in the Fischer controversy about Germany's responsibility for the outbreak of the First World War was the imperial chancellor Theobald von Bethmann Hollweg. On the basis of the controversial diary of his personal assistant Kurt Riezler, this article revisits the policy of the civilian leader of the German government, characterized by a 'defensive aggressiveness'. Fearing the growth of Russian power and closer Anglo-French cooperation, Bethmann was willing to run a 'calculated risk' by backing a local Balkan war in which Austria could defeat Serbia, while risking a continental war with Russia and France in order to split the Entente. This gamble failed due to the Russian decision for general mobilization, German military ...