How dud the assassination of the archduke of austria-Hungary lead to war between Russia and Germany?

Well, Archduke Franz Ferdinand was not well like but he was a noble. At the the time tension between Serbia and Austria Hungry were high after the split because because Serbia wanted part of Austria to be free and Austrians believed that Serbia was part of their land. Serbia fearing that war would happen and Austria hungry would try and reclaim the land made a pact with Russia. If Serbia was attacked Russia would come to their aid. When the Arch duke was assassinated, it was believed that a Serbian was responsible so Austria attacked Serbia which mean Russia came to Serbia's aid. However Austria in Response to the tensions had made a pact with Germany saying if they went to war they would come to each others aid. This meant the neighbouring Russia and Germany would go to war with each other.