Mansfeldt and Christian both having met defeat, the international subsidies, which had been irregular, ceased. The English king had no money, Richelieu was facing a Huguenot revolt at home (abetted by his purported English and Dutch allies) and the Dutch were too shrewd a class of businessmen not to know a losing proposition when it was presented to them.
In 1627, Tilly pressed eastwards. His forces defeated the Danes at Havelberg in April, and he occupied the line of the lower Havel. On 31 May, he entered Lauenberg.
In May, 1627, Wallenstein, having occupied the line of the Elbe, rapidly cleansed Upper Silesia of the remnants of the late Mansfeldt’s armies.
This done, he turned west to join Tilly. Occupying the Mecklenburg duchies, whose dukes had in early August tendered their submission to the Emperor, he joined with Tilly at Lauenberg.
Tilly and Wallenstein pressed on through Holstein, which was practically undefended. The last Danish field army was annihilated at Grossenbrode on 14 September, 1627.
By early October, Christian IV had fled to the Danish islands. Wallenstein continued cleanup operations, taking the bishopric of Bremen, and, on 14 December, 1627, the Danish redoubt of Wölfenbuttel.
While a few fortified places remained in the hands of Christian’s troops, he had for all practical purposes been ejected from the mainland. He was, however, secure on his islands and in Scandinavia: however powerful the Emperor might be on land, he was utterly berift of naval power.
Denmark having been driven into the sea, Wallenstein and his Imperial master were at the height of their powers.
Wallenstein’s armies continued to grow. He recruited ceaselessly, until at their height his forces boasted 100,000 men under arms. His armies overspread the Empire like locusts, battening on the lands of friend and foe alike. His commanders answered to no prince but Wallenstein and their Emperor.
In September, 1627, Wallenstein received from the hand of his Emperor the principality of Glogau in Silesia.
The Emperor also rewarded his own: the rich Protestantized bishoprics of Magdeburg and Halberstadt were given over to his younger ecclesiastical son Leopold William.
The Catholic League, which might have been expected to support the army of their Imperial ally, began to criticize Wallenstein. As early as April, 1627, the League, in its meeting at Bingen, officially complained to the Emperor about Wallenstein’s exactions.
These calls were renewed, and the voices of the Electors of Saxony and Brandenburg added to them, at the Electoral Diet at Mühlhausen in October, 1627. A deputation under Johann-Georg was even sent to Vienna, but received no satisfaction.
At the same Diet at which Wallenstein was being excoriated, the Catholic Electors (with no sense of irony whatsoever) began to demand their share of the spoils which Wallenstein had won. They demanded that the lands which had been taken from the Church and retaken by Wallenstein’s sword, should be restored to the primacy of the Roman faith.
The Dukes of Mecklenburg, who had supported the Danes, found their lands seized and given over to Wallenstein. In 1627, the Emperor gave out that they were held in pledge by Wallenstein to secure his expenditures on the war (although secretly he had invested Wallenstein with full ownership).
Eighteen months later, the deception was ended, and Wallenstein was publicly invested with the Duchies. The general was now not merely a prince of Bohemia, but an Imperial duke as well. The ancient houses of Germany were shocked that a duchy dating back to the 12th century could be casually disposed of to this parvenu.
Having seen Christian IV flee to the Baltic islands without possibility of Imperial pursuit, Wallenstein was intent on the creation of an Imperial sea power.
Part of the impetus for this plan came from the Emperor’s Spanish cousins. Keenly aware of the dependency of the Dutch on the coastwise Baltic trade, the Spanish were intent of disrupting that commerce.
Olivares, favorite of the King of Spain, had the Emperor proclaim Wallenstein “Admiral of the Baltic Sea”. Wallenstein was to use the gains he had made in the Danish war to reduce the Baltic to a Spanish lake.
In furtherance of this plan, the Emperor dispatched Eggenberg to the Hanseatic League meeting at Lübeck in February, 1628. The Hanse were to be granted a trading monopoly with Spain and the Spanish Netherlands. In turn they were to provide naval support for the destruction of the Dutch Baltic trade.
The Hanseatic cities, intent on profit and with a fine sense of the naval balance of power, refused to oppose themselves to the Dutch. The Emperor was refused with polite excuses, but refused nonetheless.
After the rebuff from the Hanseatic cities, Wallenstein determined to build a fleet of his own, based at Wismar in Mecklenburg and under the command of the Spaniard de Roy. However, the ships built were too small to stand up to proper warships, and the general’s land soldiers were unable to make seamen of themselves.
The Swedes and Danes were willing to fight each other for dominion of the Baltic; they were equally willing to unite to see that dominion kept from Madrid and Vienna.
Despite their traditional enmity, the two Scandinavian powers entered into a treaty of alliance in January, 1628. The Swedes were to have free passage of the Sound, while binding themselves to maintain a fleet in the Baltic.
By the Capitulation of Franzburg, signed 10 November, 1627, Bogislav XIV, Duke of Pomerania, had consented to garrisoning of his city of Stralsund by Wallenstein's troops. The city, however, had long been on bad terms with its Duke, and did not wish to allow Wallenstein’s troops within its walls.
Wallenstein dispatched von Arnim to garrison the place. While negotiating with the Stralsunders, on 4 February, 1628 he suddenly occupied the island Dänholm which commanded the harbor. Von Arnim, fleetless, was unable to resupply the troops he had trapped on this desert island. The stranded force surrendered on 5 April, 1628.
Von Arnim’s occupation of Dänholm did, however, succeed in enraging the Stralsunders. They sent embassies to the Kings of Denmark and Sweden pleading for aid.
Stralsund was surrounded by marsh on the landward side and could be easily re-supplied from the sea. Wallenstein, the “Admiral of the Baltic Sea,” had no fleet and thus was powerless to starve out the inhabitants. Von Arnim nonetheless commenced a formal siege on 13 May, 1628.
The Danes sent several regiments under Holk, including Munro’s Scottish regiment.
The Swedes followed on 23 June, 1628 with a smaller force and a demeaning treaty, which the desperate Stralsunders were obliged to accept. Wallenstein had appeared with a large force, swearing to take the place “though it be bound to heaven by chains.”
Notwithstanding this vow, after a series of assaults on 26 through 28 June, 1628 were repelled, Wallenstein negotiated a truce and a month or so after finally slunk away.
Even after the Imperials had removed themselves, the Swedes continued to maintain a large garrison in Stralsund. Gustavus Adolphus had his first foothold on the German mainland,
Christian IV of Denmark, encouraged by his successes at Stralsund, assembled another army off the German coast on the Island of Usedom. This landed at the mouth of the Oder and progressed as far as Wolgast, taking the place on 3 August, 1628. There it was met by Wallenstein's forces, and, on 12 August, 1628, Christian was once again defeated and driven back to the sea. This was the final straw for Christian, who sued for peace.
In March, 1629, Wallenstein detached a force from his armies which marched east to Poland to assist Sigismund of Poland in his ongoing war with the Swedes.
Although the Imperial forces were of some assistance to the Poles, they did not prove decisive and the Swedes maintained their positions in Poland.
Encouraged by Stralsund’s successful resistance to the Emperor, six of the Hanseatic cities, together with the Archbishopric of Magdgeburg, entered into a defensive alliance, brokered by Sweden. With this alliance of the major Northern ports, the “Admiral of the Baltic Sea” was now truly landlocked.
Wallenstein sought to impose a garrison on Magdeburg, but the city successfully resisted his besieging army. Contenting himself with token tribute of 30,000 Reichthaler, he withdrew.
Wallenstein, who had been granted plenipotentiary powers by the Emperor, made a final peace with Christian at Lübeck on 22 May, 1629.
Given the completeness of Denmark's defeat, the terms were remarkably favorable. Christian’s Danish realms were returned to him; he forfeited only the lands and titles held by his dynasty within the Empire. Nonetheless, easy though the terms were, the Protestant’s champion was out of the war.
Gustavus Adolphus was prepared to do more than dabble in Germany. But before he could think of intervening further in the Empire, he would have to settle his current war against his cousin Sigismund of Poland.
The French and English, needing an ally against the Habsburgs, were willing to mediate. Sigismund, who had done poorly in the war, was willing to treat. As a result, a six-years’ truce was agreed in Altmark on 26 September, 1629.
Gustavus occupied the island of Rugen, located in the Baltic opposite Stralsund. If he did determine to invade, he had another foothold from which to do so.
Since 1627, the south German Catholic powers had been urging the Emperor to take advantage of the victories of the Imperial arms to restore Catholic lands usurped by Protestants since the Peace of Augsburg.
A piecemeal re-Catholicization had taken place in the lands taken from the Protestants since the beginning of the war. Ferdinand, desirous of assuring his position both in heaven and as the leader of the German Catholics on Earth, was willing to formalize these gains.
The result was the Edict of Restitution. This brief document purported to do no more than enforce the terms of the Peace of Augsburg; however, the interpretation put on that document was that which had been urged by partisans of Catholicism.
According to Catholics, the right of a ruler to alter his religion and with it the religion of his subjects (cuius regio eius religio) admitted of one exception. If the ruler was a bishop or other ecclesiastical ruler, if he were to alter his religion his office was forfeit, and he must perforce be replaced in his position by a Catholic.
The Roman Church was to be restored to all lands taken from her since the Peace of Passau in 1552 or Peace of Augsburg in 1555 (depending of the form of land tenure).
Imperial commissioners were appointed to establish the ownership of the lands at the relevant date. These commissioners tended to be churchmen interested in the outcome, Catholic zealots or both.
The exception to cuius regio eius religio principle previously recognized permitting the practice of Lutheranism in Catholic states if the religion had been practiced prior to the Peace of Augsburg was to be rescinded
The Edict would result in the transfer of vast lands in Protestant Northern Germany. Ferdinand and Maximilian were able to bestow rich bishoprics upon the ecclesiastical members of their dynasties.
The triumph of Wallenstein’s arms and Ferdinand’s Counterreformation policy were to have dire consequences for both.
Naturally, the Protestant Princes, faced with dispossession of all of the Church lands they had arrogated to themselves over the last three-quarters of a century, vehemently opposed the Edict. Even the normally passive John George of Saxony declared his opposition to the Emperor. He proposed to convene a meeting of the Protestant Princes in Leipzig, the so-called Leipzig Colloquy
The Catholic victors also set to quarrelling among themselves. The Emperor had granted his ecclesiastical son Archduke Leopold William, the Bishoprics of Halberstadt and Magdeburg. But he also wished to grant him Hildesheim and Bremen. However, Maximilian wished to dispose of these to his own churchly relatives, notably his brother, the Elector of Cologne.