On 3. July 1866, European history takes a dramatic turn at the bloody Battle of Königgrätz when the Prussians vanquish the Habsburg and Saxon armies. The Prussian victory is a decisive moment in the struggle for dominance of the German Empire and sets Germany on a course that will, eventually, lead to a unified nation-state. This Universum History co-production explores how the dramatic events of the summer in 1866 occurred and how they continue to echo through history. Descendents of those involved in the battle and Austrian historians provide captivating details and place the battle and its consequences in historical context. Partially filmed on location at the site of one of the biggest battles the world had ever seen, this documentary examines how both the course of European history and the lives of those involved in the momentous clash of armies and ideologies were changed forever.