The Treaty of Lübeck concluded the Danish phase of the Thirty Years' War, forcing King Christian IV of Denmark to abandon his territorial ambitions in northern Germany and withdraw from the conflict. The Holy Roman Emperor Ferdinand II, buoyed by the victories of his general Albrecht von Wallenstein, restored Danish lands but demanded Denmark's permanent neutrality in imperial affairs, marking the high point of Habsburg power before Swedish intervention reversed the tide.
Christian IV of Denmark had entered the Thirty Years' War in 1625 hoping to expand Danish influence over northern German bishoprics and check the growing power of the Catholic Habsburgs. His campaign collapsed disastrously against the combined forces of Wallenstein and Johann Tserclaes von Tilly, culminating in crushing defeats that left Danish forces scattered and demoralized.
The Peace of Lübeck, signed July 7, 1629, was remarkably lenient in one respect: Ferdinand II restored all of Christian's conquered territories rather than annexing them outright. But the price was steep humiliation. Denmark had to renounce any further involvement in German affairs and effectively withdraw from great-power politics in the region for a generation.
The treaty marked the zenith of Habsburg and Catholic League dominance in the war. Ferdinand, emboldened, issued the Edict of Restitution just months later, reclaiming Protestant-held church lands and pushing his advantage too far. Sweden's Gustavus Adolphus would soon enter the war, and the pendulum of fortune swung dramatically against the Emperor within two years.