Chapter 21 – World War I Essential Question – “What were the causes and effects of WWI?” Main Ideas and Events 1914 1. Archduke Ferdinand was assassinated in June. 2. Austria-Hungary declared war on Serbia in July. 3. In August, Germany declared war on Russia and France and invaded Belgium. This was the start of WWI. 1915 1916 1.In May a German UBoat torpedoed the British passenger ship Lusitania Killing 128 Americans. 1.In February the Germans launched a major offensive at the Battle of Verdun 2. The Allies began their offensive at the Battle of the Somme 3. In November, Woodrow Wilson won the US presidential election. 1917 1. 2. 3. 4. 5. The Germans sent Mexico the Zimmerman Telegram in January requesting an alliance if the USA entered the war. March saw German attacks and sinking of 4 American ships. The US Congress declared war on Germany in April. The draft, or Selective Service Act, went into effect in May. Russia withdrew from the war in December. 1918 1919 1. In March, 1. World leaders met at the Paris Peace Conference In January. Wilson’s 14 points were influential. 2. In June, the Allies and Germany signed the Treaty of Versailles. 3. The League of nations came into existence. the treaty of Brest-Litovsk shifted German forces to the Western Front. 2. The Battle of the Argonne Forest helped turn the tide of war in favor of the Allies. 3. Germany became a republic and agreed to an armistice. 1920 The US Senate rejected the Treaty of Versailles and the League of Nations.