Thirty Years' War: Four thousand Swedish troops under Gustavus Adolphus land in Pomerania, Germany.

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.

Gustavus Adolphus, also known in English as Gustav II Adolf or Gustav II Adolph, was King of Sweden from 1611 to 1632, and is credited with the rise of Sweden as a great European power. During his reign, Sweden became one of the primary military forces in Europe during the Thirty Years' War, helping to determine the political and religious balance of power in Europe. He was formally and posthumously given the name Gustavus Adolphus the Great by the Riksdag of the Estates in 1634.

Pomerania is a historical region on the southern shore of the Baltic Sea in Central Europe, split between Poland and Germany. The central and eastern part belongs to the West Pomeranian, Pomeranian and Kuyavian-Pomeranian voivodeships of Poland, while the western part belongs to the German states of Mecklenburg-Western Pomerania and Brandenburg.