The Thirty Years' War, a protracted and catastrophic conflict, raged from 1618 to 1648, primarily within the borders of the Holy Roman Empire. Often regarded as one of the most devastating wars in European history, it is estimated that between 4.5 to 8 million people perished as a result of the conflict, with some regions of Germany experiencing population losses exceeding 50%. This war, though often thought of in isolation, was deeply interconnected with several other significant European conflicts, including the Eighty Years' War, the War of the Mantuan Succession, the Franco-Spanish War, and the Portuguese Restoration War.


For much of the history of the conflict, historians regarded the Thirty Years' War as a continuation of the religious struggles that had begun during the Reformation and were seemingly concluded with the Peace of Augsburg in 1555. The Peace of Augsburg had divided the Holy Roman Empire into Catholic and Lutheran states, but the rapid spread of Protestantism, particularly beyond these established boundaries, steadily eroded Imperial authority in the years that followed. While religion undeniably played a role in sparking the conflict, scholars generally agree that the broader struggle for European supremacy between the Habsburgs of Austria and Spain, and the House of Bourbon in France, fueled the war's escalation and far-reaching impact.