Horses and mules were extremely important during WWI. This image depicts horses and troops from New Zealand at a watering point in Louvencourt, France on May 31, 1918. Photo by Henry Armytage Sanders; online courtesy Royal New Zealand Returned and Services' Association Collection, Alexander Turnbull Library, Wellington, New Zealand.
After Franz Ferdinand was assassinated, the Austro-Hungarians demanded an apology from Serbia. (Recall that Gavrilo Princep was a Bosnian Serb and he, plus many other Serbs, wanted their independence from the Austro-Hungarian Empire).
Was there evidence that Serbian authorities knew about the assassination plot? It depends on which authorities one examines. If military intelligence, the answer is likely "yes" since it appears that "the plot to assassinate Franz Ferdinand led straight to the Serbian chief of military intelligence..." (See The European Powers in the First World War: An Encyclopedia by Spencer Tucker, at al, at page 531.)
Whether the Empire's decision makers knew or did not know about the involvement of Serbia's military intelligence leader, the Austrian government issued an extremely harsh ultimatum to Serbia.
Despite its drastic terms - written as though Austria was simply looking for a war excuse - Serbia accepted all but two provisions. Perhaps Austria's leaders thought any war against Serbia would be over quickly (and with few casualties). That, however, is not how things worked out.
At the time, Europe's major powers had varying alliances with other European countries. Britain, for example, had guaranteed Belgium's neutrality; Russia had pledged to support Serbia; Germany was allied with the Austro-Hungarian Empire.
If war were declared, it would trigger a cascading effect of countries lining up against each other - even if there seemed to be no good reason for a major conflict beyond the alliances.
Many of Europe's monarchs were Queen Victoria's grandchildren. Had Britain's long-ruling Queen been alive during the summer of 1914, perhaps she could have stopped her squabbling descendants from going to war, despite the preexisting alliances.
Who were the British Queen's grandchildren (who eventually declared war on each other's countries)?
Soon after Franz Ferdinand's death, when saber-rattling by Austria's leaders toward Serbia began to look like ominous war clouds, the Tsar feared that his own military men were looking forward to joining the conflict. To avoid a catastrophe, the Tsar sent a telegram to the Kaiser:
...In this serious moment, I appeal to you to help me. An ignoble war has been declared to a weak country...I foresee that very soon I shall be overwhelmed by the pressure forced upon me and be forced to take extreme measures which will lead to war. To try and avoid such a calamity as a European war I beg you in the name of our old friendship to do what you can to stop your allies from going too far. (Nicholas II to Kaiser Wilhelm II, 29 July 1914.)
Meanwhile, Willy had sent a telegram to Nicky (which crossed in the wires):
It is with the gravest concern that I hear of the impression which the action of Austria against Serbia is creating in your country ... I fully understand how difficult it is for you and your Government to face the drift of your public opinion. Therefore, with regard to the hearty and tender friendship which binds us both from long ago with firm ties, I am exerting my utmost influence to induce the Austrians to deal straightly to arrive to a satisfactory understanding with you ...Your very sincere and devoted friend and cousin - Willy
Soon after this exchange, Austria-Hungary began mobilizing its troops against Serbia. Nicky and Willy sent more telegrams to each other, in an effort to stop the madness, but cooler heads did not prevail. Then ... Russian generals also began to mobilize their troops.
After analyzing many primary-source documents leading up to the war - including Austria's ultimatum and Serbia's reply - Charles F. Horne (who assembled those many records into a multi-volume Source Records of the Great War) concluded:
The Great War could no more have been avoided than an earthquake or any other cataclysm of Nature's Unknown Forces. (Source Records of the Great War, Vol 1, edited by Charles F. Horne, page xvii.)
Mechanized warfare - with machines moving heavy artillery from place to place - was not part of a battle scene during the summer of 1914. It had only been eight months since Henry Ford introduced a moving-chassis "assembly line," at his Detroit-based Model-T car factory, so horses (among other animals) would have to carry the men and the weight in this "war to end all wars."
Joey - Albert Narracott's thoroughbred - would be part of the effort.