Summer 1914. Archduke Ferdinand's assassination in Sarajevo set off a chain of alliances that turned a regional crisis into the opening of the First World War. When Austria-Hungary declared war on Serbia, the plan was to knock Serbia out quickly before turning to face Russia. The first invasion failed. The second stalled. The third — with victory seemingly moments away — ended in another humiliating defeat. It took a German intervention the following year to finally conquer the country. This rarely examined corner of the war is the focus of a wargame built around Serbia's against-the-odds resistance.