A month after the assassination of Archduke Franz Ferdinand, the crisis developed with lightning speed. On July 23 Austria-Hungary presented Serbia with an ultimatum designed to be rejected. The ultimatum required the government of Serbia to take such humiliating steps as dismissing military and civilian officials to be named by Austria-Hungary. At the same time, officials of the Austro-Hungarian government were to be allowed to participate in Serbia's investigation of the plot to murder the archduke. The inevitable rejection was Austria's excuse to attack Serbia five days later. Russia's support for the Serbs took the form of a military mobihzation along its entire western frontier. In short order, Germany responded with a declaration of war against Russia on August 1 , then against France, Russia's ally, two days later. When Germany implemented its long-standing war plan and invaded France through Belgium on August 4, Britain immediately joined France and Russia. When this momentous crisis arrived, a mixture of European crowned heads, civilian leaders, and military commanders moved to meet it. In Germany, Kaiser Wilhelm played an active role in the decision to support Austria's ultimatum to Serbia. Thereafter Prime Minister Bethmann Hollweg and General Helmuth von Moltke took the lead, and the kaiser merely ratified the decision to go to war. In the other great monarchies of the timeŚAustria-Hungary, Russia, and Great BritainŚmonarchs had a lesser role. In Austria-Hungary, Foreign Minister Count Leopold von Berchthold took command and decided on war. In Russia, Foreign Minister Sergei Sazonov set the country's policy and persuaded a hesitant Tsar Nicholas II to follow. In Vienna and St. Petersburg (renamed Petrograd in late August 1914), as in Berlin, the generals commanding their countries' armiesŚConrad von Hotzendorf, Nikolai Yanushkevich, and von MoltkeŚpressed for national mobilization and, in so doing, brought each country measurably closer to a declaration of hostilities. By contrast, in Britain, with military leaders far from the inner circle of power, the civilians in the cabinet, Prime Minister H. H. Asquith and his colleagues, decided the issue. King George V ratified their decision. In the hostilities now beginning, monarchs would fade even further into the background, and, in most of the belligerent states, generals and statesmen would wrestle for control of the war effort.