Who did germany & austria-hungary declare war on due to the assassination of archduke franz ferdinand

Serbian hatred of Austria resulted in the formation of many secret anti-Austrian societies in Serbia. On June 28, 1914, a member of a Serbian secret party shot and killed Archduke Francis Ferdinand, heir to the Austrian throne, along with his wife. Infuriated by the action, Austria determined to punish the Serbs. Within just a few weeks, the countries of Europe were preparing for war, even though no one believed that war would come. Leaders of most nations still made their travels, visited one another, and planned for state visits to each other's countries.