The first important event of course would be the assassination of Archduke Franz Ferdinand and his wife Sophie in Sarajevo on June 28, 1914. The following are important events thereafter:
- The Austrian declaration of war against Serbia on July 28, 1914.
- Russian mobilization against Austria and Germany on July 29, 1914, followed by the German declaration of war against Russia.
- Germany's declaration of war against France on August 4, 1914.
- Britain's declaration of war against Germany for violation of Belgian Neutrality on August 5.
- Implementation of Germany's Schlieffen Plan which would allow it to fight a war on two fronts; but which failed when German troops were stopped short of Paris.
- British Blockade of Germany's North Sea ports, followed by Germany's attempt to blockade the entire British Isles.
- Sinking of RMS Lusitania in May, 1915 by a German unterseeboot. Outrage in the United States led to the issuance of the Arabic Pledge by Germany which promised not to attack civilian shipping without warning. This was an attempt to keep the U.S. out of the war.
- The Battle of Verdun, a failed German offensive which led to tremendous loss of life on both sides. As a result, Germany ordered full mobilization of the entire country. General von Hindenburg told the German people that Germany could win the war:
if all the treasures of our soil that agriculture and industry can produce are used exclusively for the conduct of war…All other considerations must come second.
- German resumption of Unrestricted Submarine Warfare (sinking ships without warning) in Spring, 1917. Thereafter, the U.S. broke diplomatic relations with Germany.
- Interception of the Zimmerman Telegram by the British which was passed on to the U.S. in April, 1917. In the telegram, Germany proposed an alliance with Mexico in return for which Mexico would receive from the U.S. territories lost in the Mexican War of 1848. This led to a formal declaration of war by the U.S.
- The Russian Revolution which led to Russia's withdrawal from the war on March 3, 1918 by the Treaty of Brest-Litovsk.
- The Meuse-Argonne offensive of October-November, 1918, the bloodiest battle of the war which ultimately led the Allies to break through German lines.
- The collapse of governments within the Central Powers, primarily to abdication of Kaiser Wilhelm II. This was largely the result of intense shortages occasioned by the war and communist agitation.
- The signing of the Armistice at Aix-la-Chappelle on November 11, 1918, which marked the end of hostilities.
- The Versailles Peace Conference of 1919 which adjusted the map of Europe and imposed harsh terms on Germany; so much so that the failures of the treaty are a primary element in the outbreak of World War II.