Answer:
Step-by-step explanation:
The Arch Duke was assassinated because of the imperialist and ill-treatment of minorities within the empire by the current leader and leaders before him. War began after Serbia refused to complete the ultimatum that was made with the idea of them refusing to fulfill it since it was almost impossible to do so. After that Austria-Hungary attacked Serbia who was protected by Russia. After Russia joined the war Germany joined the war then France joined to protect Russia. Britain joined the war after Germany attacked Belgium that was guaranteed by Britain. A lot more led to the start of world war 1 but this is the simplest form.