After Lützen, Wallenstein had retired into Bohemia, where his troops spent the winter battening on the Habsburg ancestral lands.
The Swedish army cleared Saxony of Wallenstein’s garrisons and then retreated to winter quarters in Franconia. In December, 1632, Swedish troops under Horn removed the Imperial forces from the Alsace. A force under Georg of Brunswick-Lüneberg and Wilhelm of Hesse-Kassel attacked across the Weser, taking the Bishopric of Paderborn and the Abbacy of Fulda.
The death of Gustavus left a dangerous vacuum in both Sweden and Germany. Gustavus’s sole heir was Princess Christina, who was all of six years old. Her mother, Maria-Eleonora of Brandenburg (sister to the Elector), was unstable and ill-suited to act as her daughter’s regent.
The Swedish State Council determined that the regency should be in the hands of a committee of nobles and that Axel Oxenstierna, Gustavus’s faithful Chancellor, should both head that body and be Swedish proconsul in the Empire.
Oxenstierna’s first priority was to regularize relations between the Protestant princes of Western Germany and the Swedes.
Soon after Lützen, Oxenstierna had pulled units of Swedish national troops back to the Baltic. Gustavus’s conquests in the Rhineland were to be maintained, if at all, by the Germans themselves.
A meeting of the princes of the Upper and Lower Rhenish, Swabian and Franconian Circles was convened at Heilbronn in October, 1633. The Protestant electors of Brandenburg and Saxony were invited, but declined. A treaty among the Princes was signed at Heilbronn in 23 April, 1633.
Under the League of Heilbronn, each of the Circles was to contribute 2,500,000 Reichsthaler annually. The Swedes were given overall military direction of the League forces.
Richelieu dispatched the Marquis of Feuquiéres as his ambassador to Heilbronn.
At his insistence King of France was made co-guarantor of the League, on a par with the child-Queen of Sweden. Further, the Treaty of Bärwalde was renewed, with the subsidies owed Sweden thereunder thenceforth to be paid into the treasury of the League rather than that of Sweden.
Despite the contributions laid on the Heilbronn League members, the armies of Sweden remain unpaid. For some units, the arrears of pay stretched back half a decade.
During the winter of 1632-33, the officers of the Swedish armies in western Germany resorted to threats of mutiny. Oxenstierna, desperate, bought off the officers with grants of conquered land in lieu of the sums owed them. Most richly rewarded was Bernhard of Saxe-Weimar, who was made Duke of Franconia.
He authorized local garrisons to exact contributions. Further, he extracted a month’s pay from the Heilbronn League. The soldiery were temporarily contented with this license to loot, and the army returned to obedience.
Saxony remained Sweden’s most difficult ally. Johann-Georg was continually conniving with Wallenstein for a separate peace. The Saxons refused to join the Heilbronn League, and unsuccessfully attempted to dissuade the Elector of Brandenburg from joining it.
Nonetheless, the Saxons were too powerful to be ignored. In December of 1632, Oxenstierna appeared at Leipzig and persuaded Johann-Georg to join in a spring campaign against the Emperor.
As the price of his participation, Johann Georg insisted the campaign be conducted across his borders in Silesia. He also insisted that command be given to Matthias Thurn, the exiled leader of the Bohemian Defenestrators. Oxenstierna was constrained to agree.
As with the campaign east undertaken by the Swedes and Saxons in the wake of Breitenfeld, the Saxon forces were led by von Arnim, Wallenstein’s former lieutenant.
Similarly, at the outset, Wallenstein seemed more interested in negotiating than fighting. In June, soon after hostilities began, Wallenstein proposed a cease-fire. This lasted until July.
At the expiration of the cease-fire, Wallenstein sent a force under Holk raiding into southern Saxony. The raiders were decimated by the plague, which carried away Holk, and in August, 1633 the Imperials retreated into Silesia. Wallenstein promptly proposed another cease-fire to last until September.
Finally, in early October, Wallenstein struck. He attacked Thurn’s headquarters at Steinau. 8,000 Swedish troops were captured, along with Thurn himself. Thurn turned over all of the occupied towns of northern Silesia as the price of his freedom.
Wallenstein then moved forward through Lusatia to the line of the River Oder, from whence he attacked Brandenburg and Saxony.
In an attempt to re-open the “Spanish Road” between Northern Italy and the Low Countries, the Spanish dispatched a small force under Feria, which arrived in Austria in September, 1633. He joined the remnants of the Bavarian army under Aldringer and marched west to retake Constance and lift the siege of Briesach.
The Swedish army under the alternating command of Horn and Bernhard of Saxe-Weimar moved forward against the Hispano-Bavarian force. While Horn immobilized the foe near Lake Constance, Bernhard struck deep into Bavaria. He attacked and took Regensburg on 13 November, 1633.
Maximilian of Bavaria, and the Emperor himself, had begged Wallenstein to move to defend the city. Wallenstein had refused until it was too late, not moving until 18 November, 1633. Hearing that Regensburg was already fallen, he contented himself with a feint forward into the Upper Palatinate, and a rapid return to Bohemia.
By the end of 1633, Wallenstein was distrusted by everyone, most of all his Imperial master. The generalissimo plotted with everyone against everyone else, and kept faith with no-one. The Emperor himself began to regret the plenary powers he had granted Wallenstein in the panic after Breitenfeld. The over-mighty vassal held the right to command all forces within the Empire, the right of supreme command over those forces and the right to make war and peace as he saw fit.
All those with influence over the Emperor were demanding Wallenstein be removed. Oñate, the Spanish ambassador, was outraged by Wallenstein’s assertion that, under his Imperial commission, he should have control over the Spanish army currently being assembled in Northern Italy.
The Emperor’s son, also Ferdinand, wished for a military command. Here also Wallenstein’s assertion of absolute command, stood in the way of the Prince’s ambitions.
Lamormaini, the Emperor’s Jesuit confessor, was outraged at Wallenstein’s apparent willingness to compromise the Edict of Restitution in order to make peace.
The Bavarians, the Emperor’s strongest allies within the Empire, were outraged at Wallenstein’s refusal to protect Regensburg.
The Emperor dispatched plenipotentiaries to Wallenstein’s camp at Pilsen, demanding he move his troops into Bavaria. On 12 January, 1634, Wallenstein reacted by demanding all his officers swear an oath of loyalty to Wallenstein’s own person. A clause in the oath rendering it effective only so long as Wallenstein remained in the service of the Emperor was stricken by the general’s own hand.
On 24 January, 1634 the Emperor issued an order deposing Wallenstein and setting up in his place Ferdinand of Hungary. Since the loyalties of Wallenstein’s troops remained an unknown the order was kept secret. However, it was communicated to Piccolomini and Gallas, Wallenstein’s senior generals, and to Aldringer, the general of Bavaria. Each assured the Emperor of his loyalty and began to plot Wallenstein’s downfall.
On 13 and 17 February, 1634, Piccolomini and Gallas fled Wallenstein’s camp. They then issued an order declaring Wallenstein’s command to be at an end. On 18 February, 1634, the Emperor issued a public order to the same effect. Wallenstein’s army deserted him en masse.
With his few remaining loyalists, Wallenstein fled north to Eger. There he proposed to join with the forces of von Arnim and Bernhard of Saxe-Weimar and cast his lot with the enemies of the Emperor. On 25 February, 1634, soldiers among the Eger garrison massacred Wallenstein’s adherents at a banquet in their honor and slew Wallenstein himself in his chambers.
In March, 1634, the Elector of Saxony, unable to negotiate with a dead Wallenstein, finally joined the direct talks with the Emperor organized by his brother-in-law, Georg of Hesse-Darmstadt, at Leitmeritz, Bohemia.
The Heilbronn League, meanwhile, were meeting in Frankfort-am-Main. Saxony and Brandenburg refused to join the League. The Saxons urged negotiation with Emperor. On 23 April, 1634, Brandenburg demanded the Swedes evacuate Pomerania, which the Swedes refused to do. Following the Elector’s lead, neither the Upper nor Lower Saxon Circles would join the League, and it remained primarily an organization of Protestant princes from the southwest.
The financial and organizational weakness of the League was becoming manifest. The French were not slow to turn the situation to their advantage: in early September, 1634 the League turned over the mighty Rhine fortress Phillipsburg in return for a promise of French assistance against the renewed Hispano-Imperial offensive.
With Wallenstein dead, Ferdinand, King of Hungary, was given command of the Imperial forces. His cousin, Ferdinand, Cardinal-Infante of Spain, was given command of the Spanish expeditionary force in Northern Italy. The two Ferdinands were to join their forces and push west, clearing the “Spanish Road” between Northern Italy and the Low Countries.
The King of Hungary joined with the Bavarian troops under Aldringer in an attack on Regensburg. They retook that city on 22 July, 1634 and pushed west down both banks of the Danube, taking Donauwörth in August, and besieging the city of Nördlingen.
Meanwhile, the Swedish forces under the joint command of Horn and Bernard of Saxe-Weimar pushed eastward to meet the assault. Taking Aldshut by storm and killing its commander Aldringen, they reached the vicinity of Nördlingen on 23 August, 1634.
The command of the Swedish army was divided between Horn and Saxe-Weimar. The command alternated daily: on one day one was the supreme commander, on the next the other. This bizarre allocation of authority between two very different commanders was to have disastrous results: if the Swedes had attacked upon arrival at Nördlingen, as the fiery Saxe-Weimar demanded, Ferdinand of Hungary’s army would not have been reinforced by his cousin’s Spanish troops; if the Swedes had delayed their attack until 6,000 reinforcements under Rhinegrave Otto-Ludwig arrived as the cautious Horn proposed, they would not have been outnumbered.
The attack on the Imperial forces was delayed until 5 September, 1634. By that time, unbeknownst to Horn and Saxe-Weimar, the Bavaro-Imperial forces had been reinforced by the arrival of the Cardinal-Infante and the Spanishtercioson 3 September, 1634. The Swedes, whether they knew it or not, were badly outnumbered. After an unsuccessful assault on the trenches on 5 September, 1634, on 6 September, 1634, the Swedes attacked the prepared positions of the combined forces. After a series of failed assaults against the hilltop on which the Spaniards were entrenched, Horns forces retreated behind Bernhard’s line. Just at that moment, the Imperial cavalry attacked. Bernhard’s line was broken and the Swedish army dissolved in chaos.
By the end of the day, the Swedish field army ceased to exist. Horn was captured and Bernhard fled westward, calling his garrisons to join him, hoping to make a stand, if at all, at the Rhine.