The Archduke had been shot and killed while on a visit to Sarajevo in Bosnia. The assassin, Gavrilo Princip, was a Serbian nationalist who opposed Austria-Hungary’s annexation of Bosnia that had taken place in 1908. Austria-Hungary condemned the attack but only began preparations for a formal response after consulting with Germany, its closest ally. Kaiser Wilhelm II met with the Austrian-Hungarian ambassador on 5th July, and gave assurances that Germany would support military action against Serbia in what is known as the ‘Blank Cheque’. Having secured the support of the strongest army in Europe, the Austro-Hungarian Crown Council began preparations to force a military conflict with Serbia. The intention was to secure a swift Austrian victory before Serbia’s powerful ally, Russia, was able to intervene. The Crown Council decided that an ultimatum containing unacceptable demands would be the best course of action, and presented the terms to Serbia on 23rd July. Austria-Hungary’s Emperor Franz Josef ordered mobilisation after Serbia agreed to all but one of the demands at the end of the 48-hour deadline. This response alarmed the other countries of Europe, including Britain who called for mediation. This was rejected by Vienna on the advice of Germany and, at 11am on 28 July, Emperor Franz Josef signed the declaration of war against Serbia. It was sent by telegram to the Serbian government in Belgrade ten minutes later, making it the first declaration in what was to become the First World War.