Answer:
Austria attacked Serbia. A Serbian rebel had assassinated the Archduke Franz Ferdinand, which sparked the anger of the Austrians. They attacked Serbia in order to avenge their Archduke.
Explanation:
WWI began in 1914, after the assassination of Archduke Franz Ferdinand of Austria, and lasted until 1918. During this conflict, Germany, Austria-Hungary, Bulgaria and the Ottoman Empire; also known as the Central Powers,fought against, Japan, Russia, France, Italy, Romania, Great Britain, and the US; also known as the Allied Powers. A Serbian rebel had assassinated the Archduke Franz Ferdinand, which sparked the anger of the Austrians. They attacked Serbia in order to avenge their Archduke.
