<ins class="ice-ins ice-cts-1" data-changedata="" data-cid="2" data-last-change-time="1576165642522" data-time="1576165642522" data-userid="162" data-username="Author">World War I&nbsp;(often abbreviated as&nbsp;WWI&nbsp;or&nbsp;WW1), also known as the&nbsp;First World War, the&nbsp;Great War, the&nbsp;Seminal Catastrophe, and initially in North America as the&nbsp;European War, was a&nbsp;global war&nbsp;originating in&nbsp;Europe&nbsp;that lasted from 28 July 1914 to 11 November 1918. Contemporaneously described as &quot;the war to end all wars&quot;,[7]&nbsp;it led to the mobilisation of more than 70&nbsp;million&nbsp;military personnel, including 60 million Europeans, making it one of the largest wars in history.[8][9]&nbsp;It is also&nbsp;one of the deadliest conflicts in history,[10]&nbsp;with an estimated nine million&nbsp;combatants&nbsp;and seven million&nbsp;civilian&nbsp;deaths as a direct result of the war, while&nbsp;resulting genocides&nbsp;and the resulting&nbsp;1918 influenza pandemic&nbsp;caused another 50 to 100 million deaths worldwide.[11]<br />
On 28 June 1914,&nbsp;Gavrilo Princip, a&nbsp;Bosnian Serb&nbsp;Yugoslav nationalist,&nbsp;assassinated&nbsp;the Austro-Hungarian heir&nbsp;Archduke Franz Ferdinand&nbsp;in&nbsp;Sarajevo, leading to the&nbsp;July Crisis.[12][13]&nbsp;In response, on 23 July Austria-Hungary issued an ultimatum to&nbsp;Serbia. Serbia&#39;s reply failed to satisfy the Austrians, and the two moved to a war footing.<br />
A network of interlocking alliances enlarged the crisis from a bilateral issue in the&nbsp;Balkans&nbsp;to one involving most of Europe. By July 1914, the&nbsp;great powers&nbsp;of Europe were divided into two coalitions: the&nbsp;Triple Entente&mdash;consisting of&nbsp;France,&nbsp;Russia, and&nbsp;Britain&mdash;and the&nbsp;Triple Alliance&nbsp;of&nbsp;Germany,&nbsp;Austria-Hungary, and&nbsp;Italy&nbsp;(the Triple Alliance was only defensive in nature, allowing Italy to stay out of the war until&nbsp;April 1915, when it joined the&nbsp;Allied Powers&nbsp;after its relations with Austria-Hungary deteriorated).[14]&nbsp;Russia felt it necessary to back Serbia and, after Austria-Hungary shelled the Serbian capital of&nbsp;Belgrade&nbsp;on the 28&nbsp;July, approved partial mobilisation.[15]&nbsp;Full Russian mobilisation was announced on the evening of 30&nbsp;July; on the 31st, Austria-Hungary and Germany did the same, while Germany demanded Russia demobilise within twelve hours.[16]&nbsp;When Russia failed to comply, Germany declared war on Russia on 1&nbsp;August in support of Austria-Hungary, with Austria-Hungary following suit on 6&nbsp;August; France ordered full mobilisation in support of Russia on 2&nbsp;August.[17]<br />
German strategy for a war on two fronts against France and Russia was to rapidly concentrate the bulk of its army in the West to defeat France within six weeks, then shift forces to the East before Russia could fully mobilise; this was later known as the&nbsp;Schlieffen Plan.[18]&nbsp;On 2&nbsp;August, Germany demanded&nbsp;free passage through Belgium, an essential element in achieving a quick victory over France.[19]&nbsp;When this was refused, German forces invaded Belgium on 3&nbsp;August and declared war on France the same day; the Belgian government invoked the&nbsp;1839 Treaty of London&nbsp;and in compliance with its obligations under this, Britain declared war on Germany on 4&nbsp;August.[20][21]&nbsp;On 12 August, Britain and France also declared war on Austria-Hungary; on the 23&nbsp;August,&nbsp;Japan&nbsp;sided with Britain, seizing German possessions in&nbsp;China&nbsp;and the Pacific. In November 1914, the&nbsp;Ottoman Empire&nbsp;entered the war on the side of the Central Powers, opening fronts in the&nbsp;Caucasus,&nbsp;Mesopotamia, and the&nbsp;Sinai Peninsula. The war was fought in and drew upon each power&#39;s colonial empire as well, spreading the conflict to&nbsp;Africa&nbsp;and across the globe. The Entente and its allies would eventually become known as the&nbsp;Allied Powers, while the grouping of Austria-Hungary, Germany and their allies would become known as the&nbsp;Central Powers.<br />
The German advance into France was halted at the&nbsp;Battle of the Marne&nbsp;and by the end of 1914, the&nbsp;Western Front&nbsp;settled into a&nbsp;battle of attrition, marked by a long series of&nbsp;trench lines&nbsp;that changed little until 1917 (the&nbsp;Eastern Front, by contrast, was marked by much greater exchanges of territory). In 1915, Italy joined the Allied Powers and opened a&nbsp;front in the Alps.&nbsp;Bulgaria&nbsp;joined the Central Powers in 1915 and&nbsp;Greece&nbsp;joined the Allies in 1917, expanding the&nbsp;war in the Balkans. The United States initially remained neutral, though even while neutral it became an important supplier of war materiel to the Allies. Eventually, after the sinking of American merchant ships by German submarines, the declaration by Germany that its navy would resume unrestricted attacks on neutral shipping, and&nbsp;the revelation&nbsp;that Germany was trying to incite Mexico to make war on the United States, the&nbsp;U.S. declared war on Germany&nbsp;on 6&nbsp;April 1917. Trained American forces would not begin arriving at the front in large numbers until mid-1918, but ultimately the&nbsp;American Expeditionary Force&nbsp;would reach some two million troops.[22]</ins>