June 28, 1914: Assassination of Archduke Franz Ferdinand of Austria-Hungary by a Serbian nationalist in Sarajevo.
July 28, 1914: Austria-Hungary declares war on Serbia, triggering a series of alliances and declarations of war.
August 1, 1914: Germany declares war on Russia.
August 3, 1914: Germany declares war on France and invades Belgium.
August 4, 1914: Britain declares war on Germany in response to the invasion of Belgium.
August 23, 1914: Battle of Mons – First major battle between British and German forces on the Western Front.
September 5, 1914: First Battle of the Marne – Allied forces halt the German advance near Paris.
April 22, 1915: Second Battle of Ypres – First large-scale use of poison gas by the Germans.
May 7, 1915: Sinking of the RMS Lusitania – A German U-boat sinks a British passenger ship, leading to international outrage.
February 21, 1916: Battle of Verdun – One of the longest and bloodiest battles of the war begins between German and French forces.
July 1, 1916: Battle of the Somme – British and French forces launch a major offensive against German lines, resulting in heavy casualties.
February 3, 1917: United States severs diplomatic ties with Germany after German submarine attacks on American ships.
April 6, 1917: United States declares war on Germany and enters the war on the side of the Allies.
October 24, 1917: Battle of Caporetto – German and Austro-Hungarian forces launch a successful offensive against Italy.
March 3, 1918: Treaty of Brest-Litovsk – Russia signs a peace treaty with the Central Powers, effectively withdrawing from the war.
March 21, 1918: German Spring Offensive – Germany launches a major offensive on the Western Front, aiming to defeat the Allies.
July 15, 1918: Second Battle of the Marne – Allies launch a successful counteroffensive, marking a turning point in the war.
September 26, 1918: Meuse-Argonne Offensive – Largest American-led offensive of the war begins, contributing to the eventual German surrender.
October 30, 1918: Armistice of Mudros – Ottoman Empire signs an armistice with the Allies, ending its involvement in the war.
November 9, 1918: German Revolution – German Emperor Wilhelm II abdicates, leading to the establishment of the Weimar Republic.
November 11, 1918: Armistice of Compiègne – Ceasefire signed between the Allies and Germany, officially ending the war.
January 18, 1919: Paris Peace Conference begins, where world leaders gather to negotiate the terms of peace.
June 28, 1919: Treaty of Versailles is signed, imposing harsh conditions and reparations on Germany.
June 28, 1919: League of Nations is established, with the goal of preventing future wars.
March 19, 1920: Treaty of Sèvres – Peace treaty signed between the Allies and the Ottoman Empire, leading to the dissolution of the empire.
August 27, 1928: Kellogg-Briand Pact is signed, renouncing war as an instrument of national policy.
September 18, 1931: Mukden Incident – Japan invades Manchuria, marking the beginning of Japanese aggression in Asia.
July 28, 1932: Bonus Army Incident – Veterans protest in Washington, D.C., demanding early payment of bonuses promised for their service in World War I.
January 30, 1933: Adolf Hitler becomes Chancellor of Germany, leading to the rise of Nazi Germany.
September 1, 1939: Germany invades Poland, marking the beginning of World War II.
