At the height of the July Crisis in 1914, Austria-Hungary presented Serbia with an ultimatum, which set so many conditions that a rejection was expected. However, Serbia met most of the demands in its response of 25 July 1914. Kaiser Wilhelm II commented that he could no longer see a reason for war, but on the same day, Austria-Hungary declared war against Serbia.
Following the assassination of the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand, and his wife in Sarajevo, the Danube monarchy felt challenged in its position as a great power. Austria-Hungary was convinced that the neighbouring state of Serbia was behind the attack. However, there was no proof that the Serbian Government had been involved in the assassination or had known anything about it.
Nevertheless, Vienna decided to issue a tough ultimatum to Serbia in the expectation, and indeed hope, that this would be rejected. It was likely that the great power of Russia would take Serbia’s side in the conflict. Meanwhile, Austria-Hungary had received a “blank cheque” from Berlin, in which the German Kaiser wrote that he would “stand loyally by Austria-Hungary in accordance with his treaty obligations and in old friendship”.
Kaiser Wilhelm II saw no grounds for war
Then something unexpected happened. In its response to the ultimatum, Serbia surprisingly agreed to most of the demands, only refusing to accept a direct investigation by Austro-Hungarian police officers on its territory.
Kaiser Wilhelm II of Germany received a copy of the Serbian reply on 28 July 1914. On it, he wrote “A great moral success for Vienna, but with it all reason for war is gone... I would never have recommended mobilisation on this basis!” However, Austria-Hungary declared war against Serbia on the same day.
Declaration of war set a chain reaction in motion
The declaration of war set a tragic chain reaction in motion. Russia ordered its troops to mobilise. Germany felt threatened by this, and declared war against Russia on 1 August. On 3 August, Germany then declared war against France, which was allied with Russia. When the German army followed the plan devised by its former Chief of General Staff, Count Schlieffen, and invaded neutral Belgium before launching its offensive into France, Britain felt under threat and entered the war. This marked the start of the European war that gradually turned into a world war.