Three key events to note on a timeline of World War I are the assassination of Archduke Franz Ferdinand, the entrance of the United States into the war, and the signing of the Treaty of Versailles by the Germans. These events helped shaped the war.
The assassination of Archduke Franz Ferdinand in 1915 led to the beginning of the war. Following the assassination, Austria declared war on Serbia. Germany, who supported Austria, then declared war on Russia. In 1917 after years of trench warfare and stalemate war, the United States entered the conflict following the sinking of the Lusitania during Germany's unrestricted warfare campaign by submarine. The entrance of the American army tipped the scales toward the Allies, and on June 28, 1919, Germany signed the Treaty of Versailles, which outlined its terms of the reparations it was to pay back to its enemies.