The US-built Panama Canal officially opens, linking the Atlantic and Pacific Oceans.
Austria-Hungary declares war on Serbia, drawing Europe's powers into a global war that lasts until the armistice of 11 November 1918.
The Norwegian expedition led by Roald Amundsen becomes the first to reach the geographic South Pole.
The US Congress declares war on the German Empire, bringing the United States into World War I on the Allied side.
Francisco Madero calls for revolt against Porfirio Díaz, launching a decade-long revolution involving figures such as Pancho Villa and Emiliano Zapata.
An H1N1 influenza pandemic spreads worldwide, killing tens of millions of people, one of the deadliest pandemics in history.
The peace treaty ending the war between Germany and the Allies is signed in the Hall of Mirrors, imposing war guilt, territorial losses and heavy reparations on Germany.