The assassination in Sarajevo gave Austria-Hungary an opportunity to declare war on Serbia. Entangled by alliances, the other major European powers soon slipped into war as well. Germany hoped for a quick victory on the western front, before Russia had time to mobilize in the east, and invaded Belgium—the clearest way into France. French and British troops halted the Germans’ progress, then failed in their attempts to break through German lines; the stalemate lasted for nearly the entire war. In 1917, the Bolshevik revolution prompted Russia to sue for peace, which freed Germany to shift its troops to the west. Germany’s campaign to overwhelm France and Britain ended in defeat after the United States entered the war.
June 28: A Serbian nationalist assassinates Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, and his wife in Sarajevo.
July 28: Austria-Hungary declares war on Serbia.
July 31: Russia mobilizes its armed forces in support of Serbia.
August 1: Germany declares war on Russia.
August 3–4: Germany declares war on France, then invades Belgium on its way to France.
August 4: Britain declares war on Germany. The United States declares its neutrality.
August 9: The first British troops land in France.
September 5–10: The First Battle of the Marne stops Germany’s invasion of France.
September–November: Trenches are dug along the western front.
December 25: In an informal Christmas truce, enemy soldiers in the trenches play soccer and exchange cigarettes.
January–February: German air raids and a submarine blockade menace Britain’s home front.
April 22: Germans first use chlorine gas as a poison, against French and Algerian soldiers in Belgium.
May 7: A German submarine sinks the ocean liner Lusitania. That 128 of the 1,198 victims are Americans challenges their nation’s policy of neutrality.
February–December: The Battle of Verdun. Initial German advances are driven back by French counterattacks, causing hundreds of thousands of casualties.
May: The Sykes-Picot Agreement is signed. The secret pact between Britain and France, with Russia’s assent, divvies up control of the Middle East should the Allies win the war.
June 5: Encouraged by the British, Arabs begin to revolt against their Turkish rulers.
November 7: U.S. President Woodrow Wilson is reelected, after campaigning with the slogan “He kept us out of war.”
July 1: The Battle of the Somme begins with the worst day of fighting in British military history: nearly 60,000 casualties. The British and French fail to break through German lines, producing a stalemate at a cost of more than 1 million casualties.
September 2: A German airship is shot down over Britain for the first time.
February 3: The U.S. cuts off diplomatic relations with Germany because of submarine attacks on American merchant ships.
March 1: Germany is revealed as having pressed Mexico to side with it if the United States entered the war, in exchange for the return of Texas, Arizona, and New Mexico to Mexican sovereignty.
March 15: Czar Nicholas II abdicates the throne amid revolution in Russia.
April 6: At President Wilson’s behest, the U.S. Congress declares war on Germany.
June 26: The first U.S. troops arrive in France.
November 7: The Bolsheviks, led by Vladimir Lenin, take power in Russia.
December 3: The new Russian government begins armistice negotiations with the Central Powers.
December 9: British troops capture Jerusalem, ending 673 years of Muslim rule.
January 8: President Wilson’s Fourteen Points offer a vision of a postwar peace.
March 3: Russia signs a treaty with the Central Powers at Brest-Litovsk and loses territory, including Ukraine, Poland, and the Baltic states.
April 5: The first stage of Germany’s Spring Offensive, halted by British and Australian troops, ends.
May–July: American, French, and British troops stop the Germans from advancing to Paris.
July: German troops desert in large numbers as they are transferred from the eastern to the western front. Ernest Hemingway, serving as an ambulance driver, is wounded on the Italian front.
July 17: Bolsheviks murder Czar Nicholas II and his family.
August 8: The Allies force the Germans to retreat from the Somme, and the tide of the war starts to turn.
September: A series of Allied victories pierces the Germans’ defensive line.
November 9: Kaiser Wilhelm II abdicates, and the Weimar republic is established.
November 11, 10:59 a.m.: The last soldier to die in the Great War, an American private, is killed in France.
November 11, 11 a.m.: The Allies and Germany declare an armistice, effective immediately.
January 18: The peace conference begins in Paris.
February 14: President Wilson presents his draft proposal for a League of Nations covenant at the Paris Peace Conference.
June 28: The Treaty of Versailles is signed.
September 25: President Wilson collapses in Pueblo, Colorado, after three weeks of a whistle-stop campaign to promote the Treaty of Versailles and the League of Nations.
March 19: The U.S. Senate fails to ratify the Treaty of Versailles.