1848: "Year of Revolutions." Starting in France, European countries are swept up in revolution, none of which succeed, most of which end bloodily. The anti-slavery Free Soil Party divides the Democratic Party and slave-holding career soldier Zachary Taylor is elected president of the U.S..
1876: Western Union has a profound influence on the election of Rutherford Hayes as U.S. President, who lost the popular vote and won the electoral vote by 1, and not without controversy. His rival, Samuel Tilden, never conceded, and was called "President Tilden" by Democrats. (They called Hayes "Rutherfraud.")
1897: Wm. Randolph Hearst uses the New York Journal to change public opinion in favor of war with Spain, famously telling a photographer, "Your provide the photographs, I'll provide the war." The Spanish American War followed the next year.