Thirty Years' War: The Swedish Army defeats the armies of Saxony and the Holy Roman Empire at the Battle of Wittstock.

The Thirty Years' War, fought primarily in Central Europe between 1618 and 1648, was one of the most destructive conflicts in European history. An estimated 4.5 to 8 million soldiers and civilians died from battle, famine, or disease, while parts of Germany reported population declines of over 50%. Related conflicts include the Eighty Years' War, the War of the Mantuan Succession, the Franco-Spanish War, the Torstenson War, the Dutch-Portuguese War, and the Portuguese Restoration War.

The Battle of Wittstock was fought on 4 October 1636, near Wittstock in northern Germany, during the Thirty Years' War. A Swedish army commanded jointly by Johan Banér and Alexander Leslie won a decisive victory against a combined Imperial-Saxon army, led by Count Melchior von Hatzfeld and John George I, Elector of Saxony.