The following information is taken from Lincoln Journal Star.

On June 28, 1914, Austrian Archduke Franz Ferdinand was assassinated by a Serbian nationalist.

A month later, Austria-Hungary declared war on Serbia.

Then Germany and Italy joined Austria in the Triple Alliance (Central Powers), and Britain, France, and Russia, joined Serbia in the Triple Entente (Allied Powers).

Russia entered the war against Germany on aug 1, 1914.

On April 2, 1917, the U.S. president Wilson entered the war.

On Nov 11, 1918, the war ended.