World War I also known as the First World War, was a global war centered in Europe that began on 28th July 1914 and lasted until 11th November 1918.efore World War II began in 1939, World War I was called the Great War, the World War or the War to End all Wars. 135 countries took part in World War I, and more than 15 million people died in the war. World War I was fought on most of the continent of Europe.