 Spee thereafter began preparations for a cruise to German New Guinea ; Scharnhorst departed on 20 June . The two armored cruisers proceeded to Nagasaki , Japan , where they coaled in preparation for their tour . While en route to Truk in the Caroline Islands , they received news of the assassination of Archduke Franz Ferdinand , heir to the throne of Austria @-@ Hungary . On 17 July , the East Asia Squadron arrived in Ponape in the Carolines , where the ships remained while tensions steadily rose in Europe . In Ponape , Spee had access to the German radio network , and he learned of the Austro @-@ Hungarian declaration of war on Serbia on 28 July , followed shortly thereafter by the Russian mobilization — tantamount to a declaration of war — against Austria @-@ Hungary and possibly Germany . On 31 July , word came that the German ultimatum that Russia demobilize its armies was set to expire ; Spee ordered his ships ' crews to prepare for war . On 2 August , Wilhelm II ordered German mobilization against Russia and its ally , France . Following Germany 's violation of neutral Belgium during its invasion of France , Britain declared war on Germany . 
