France and Germany, ever since the Franco-Prussian War, have been arch-enemies. France, consumed by a desire for revenge and to redeem its honor, seeks to avenge its defeat. Similarly, Germany yearns to once again vanquish France and assert its dominance over the European continent.
Following the outbreak of the Sarajevo incident, France immediately sensed a looming crisis. President Raymond Poincaré urged the military to commence secret mobilization and prepare for combat. He also instructed the ambassador to Russia to establish communication with the Russian government. France and Russia had signed a military alliance treaty, which mandated that should one country face an attack from Germany, the other must respond unconditionally.
The French understood all too well that Germany's military might had expanded rapidly. Relying solely on their own strength would render them no match for Germany. Therefore, they sought the support of other nations to confront this formidable adversary. Fortunately, Germany had several rivals. Together, France and Russia could sufficiently contain Germany on land. With the backing of Britain, defeating Germany was not an impossible feat.
On the other side of the Channel, the British held a somewhat different stance. Britain had also prepared for war and believed that acting sooner rather than later would be more advantageous; any delay would only work against them. They recognized that Germany's production capabilities surpassed their own and that Germany would soon catch up in naval shipbuilding. Britain aimed to maintain its naval superiority through war in 1914 against this dangerous competitor.
However, in the aftermath of the Sarajevo incident, Britain did not initially express intentions to engage in conflict. They were concerned about Germany backing down but equally wary of the implications of being the first to instigate war. Additionally, there existed a pro-German faction within the British Parliament and Cabinet. Twelve members of the Cabinet opposed entering the war, and the entire working class, along with a majority of the Liberal Party, resisted involvement. Public gatherings in Trafalgar Square called for Britain to declare neutrality. Under the pressure of a resounding peace movement, Foreign Secretary Grey assured the German ambassador that Britain had no alliance with Russia or France and was bound by no obligations, repeatedly asserting Britain's position of "doing everything possible to prevent war among the great powers."
On July 5, the Austro-Hungarian ambassador to Germany, Count Jagow, was tasked with delivering a personal letter from Emperor Franz Joseph I to Wilhelm II. The letter stated that the assassination of the Archduke was "the direct result of incitement by Russian and Serbian Pan-Slavists; their sole aim is to weaken the Triple Alliance and disintegrate my empire... If we allow this situation to persist, it means my court and my territory will long suffer danger... After the recent horrifying events in Bosnia, you must also believe that the antagonism between Austria-Hungary and Serbia cannot be amicably resolved; unless the roots of this nefarious incitement in Belgrade are punished, the peace policy of all European monarchies will be threatened." The letter's call for punishing Serbia implied waging war against it, and Franz Joseph I implored Wilhelm II to express support for his military actions.
On July 5 and 6, Wilhelm II summoned senior military leaders and government ministers to Potsdam Palace for meetings. He relayed information about the potential for war to his subjects. The generals responded that all preparations for war were complete. The Chief of the General Staff reported, "After this audience, I have nothing more to do. The mobilization plan was finalized on March 31, 1914. The army is ready as always." This clearly indicated that Germany's war preparations were already well underway. In light of this, Kaiser Wilhelm II issued orders to prepare for war.
On July 20, President Raymond Poincaré and Prime Minister René Viviani visited Russia. The two nations mutually assured one another that should war be declared against Germany, they would fulfill their obligations as allies. In both the joint communiqué and public diplomatic settings, Russia and France repeatedly emphasized their "precious friendship," lavishly highlighting their "brotherly naval and land forces," and vowed to "loyally cooperate with their allies." During the talks, the Russian government hosted a banquet at the Winter Palace in Petersburg. There, Poincaré specifically conversed with the Austro-Hungarian ambassador, urging him to convey to the Austro-Hungarian government that they should handle their relations with Serbia "with particular caution." He stressed, "Serbia is a close friend among the Russian people, and with Russia allied with France, who knows how many terrible disputes may arise on this matter."
On July 23, Austria-Hungary issued an ultimatum to the Serbian government, demanding that Serbia comply with the following conditions: to suppress any publications inciting hatred and contempt towards the Austro-Hungarian royal family; to immediately dissolve nationalist self-defense organizations and any other groups propagating anti-Austrian sentiments; to remove any educational content that might incite anti-Austrian propaganda from educational bodies and teaching methods; to dismiss officials in the military or administrative departments identified as conducting anti-Austrian propaganda, with the names provided by the Austro-Hungarian government; to accept cooperation with relevant Austro-Hungarian governmental departments to suppress activities aimed at undermining the integrity of Austro-Hungarian territory; to take legal action with the assistance and instructions of designated Austro-Hungarian departments against those who planned or executed the assassination on June 28, 1914; to immediately arrest the two individuals identified in the preliminary Austro-Hungarian investigation; to maintain cooperation to effectively curb arms smuggling within their territory; to explain any hostile remarks made by high-ranking Serbian officials, whether within or outside Serbia, towards Austria-Hungary; and to promptly implement these measures and inform Austria-Hungary.
Serbia was willing to accept all but the fourth and fifth demands of the ultimatum. However, this was evidently not the outcome that Austria-Hungary desired.
Following the issuance of the ultimatum, Russia notified Austria-Hungary that any attack on Serbia would trigger a general mobilization and that Russia would not permit Austria-Hungary to crush Serbia and establish dominance over the Balkans. On July 26, British Foreign Secretary Grey proposed that Germany, Britain, France, and Italy mediate the discord between Austria-Hungary and Serbia. However, Britain was secretly encouraging France and Russia to confront Germany and Austria-Hungary, promising support, which bolstered their resolve.
Britain's true intentions were only fully revealed the day after Austria-Hungary declared war on Serbia. On July 29, Grey met with the German ambassador, explicitly stating that if the conflict were confined to Russia and Austria, Britain could remain neutral; however, if Germany and France became involved, "the situation would change immediately, and under certain conditions, the British government would be compelled to make an urgent decision. In such circumstances, we cannot remain idle spectators for long."