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.

The Thirty Years' War was one of the longest and most destructive conflicts in European history, lasting from 1618 to 1648. Fought primarily in Central Europe, an estimated 4.5 to 8 million soldiers and civilians died as a result of battle, famine, or disease, while parts of present-day 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.