How many countries were involved in World War I and When did the United States join World War I?
World War I lasted from 1914 to 1918. It began as a war between two European countries, Austria-Hungary and Serbia. The underlying causes of the conflict were rooted in European political and economic policies after 1871. Eventually, the war involved thirty-two countries. Twenty-eight of these countries were known as the Allies, and included Great Britain, … Read more