Answer:
Angered Austria-Hungary which declared war on Serbia
Step-by-step explanation:
Archduke Franz Ferdinand and his wife was killed by 19 year old Serbian nationalist Gavrilo Princip at point blank range. They were targeted earlier that same day by Serbian terrorists. Their death angered Austria-Hungary and ,with the support of Germany, which declared war on Serbia in 1914 28 June. A few days later Germany declared war on Russia which was Serbia ally. Germany invaded France via Belgium which resulted in Great Britain declaring war against Germany.