At the same time the Panama Canal was built, an elusive event took place in Europe. The Archduke of Austria,Franz Ferdinand, was assassinated. His murder gave Austria-Hungary the excuse to declare war on Serbia, which they thought was to blame for the Archduke's assassination. This led to country after country joining the war. This was actually the first war in which countries throughout the world participated.
There were two sides to the war. The Central Powers were mainly Germany and Austria-Hungary. TheAllieswere France, Russia, and Great Britain. Many other European countries joined later.
Why did the United States Join the War?
When the World War broke out in Europe, the United States government planned to stay neutral. But most Americans were descendants from Europe. Because of this, it was hard to stay neutral. The American people tended to side with the Allies particularly after the Germans sank a civilian ship named the Lusitania in 1915. Almost 1,200 people died on that ship and that included 128 Americans. Still, the Americans stayed out of the war.