Denmark
In 1524, King Christian II converted to Lutheranism and encouraged Lutheran preachers to enter Denmark despite the opposition of the Danish diet of 1524. Following the death of King Frederick I in 1533, war broke out between Catholic followers of Count Christoph of Oldenburg, and the firmly Lutheran Count Christian of Holstein. After losing his main support in Lübeck, Christoph quickly fell to defeat, finally losing his last stronghold of Copenhagen in 1536. Lutheranism was immediately established, the Catholic bishops were imprisoned, and monastic and church lands were soon confiscated to pay for the armies that had brought Christian to power. In Denmark this increased royal revenues by 300%.
Thirty Years' War. In 1625 Christian IV of Denmark, who was also the Duke of Holstein, agreed to help the Lutheran rulers of neighbouring Lower Saxony against the forces of the Holy Roman Empire by intervening militarily. Denmark's cause was aided by France which, together with England, had agreed to help subsidize the war. Christian had himself appointed war leader of the Lower Saxon Alliance and raised an army of 20,000-35,000 mercenaries. Christian, however, was forced to retire before the combined forces of Imperial generals Albrecht von Wallenstein and Tilly. Wallenstein's army marched north, occupying Mecklenburg, Pomerania, and ultimately Jutland. However, lacking a fleet, he was unable to take the Danish capital on the island of Zealand. Peace negotiations were concluded in the Treaty of Lübeck in 1629, which stated that Christian IV could keep his control over Denmark if he would abandon his support for the Protestant German states.
Read more about this topic: European Wars Of Religion