World War I World War I (WWI) was a global war centred in Europe that began on July 28, 1914 and lasted until November 11, 1918. The war included huge losses of life and little ground lost or won. Fought mostly by soldiers in trenches, World War I saw an estimated 10 million military deaths and another 20 million wounded. While many hoped that World War I would be "the war to end all wars," in actuality, the concluding peace treaty set the stage for World War II.