World War I Timeline

militarism was used to build strong militaries

nationalism caused tension

Franz Ferdinand was assassinated Austria-Hungary declares war on Serbia Germany declares war on Russia

Germany threatens submarine warfare German u-boats torpedoes the Lusitania Serbia is invaded by Germany, Austria, and Bulgaria

triple alliance is formed

U.S. president Wilson is reelected

Germans resume unrestricted submarine warfare United States is alerted about the Zimmerman Note The United States declares war on Germany

Treaty of Brest-Litovsk is signed between Russia and Germany

Germany ratifies Treaty of Versailles U.S. senate refuses to ratify the Treaty of Versallies