The Austrian Habsburgs responded as their Spanish cousins had hoped. In April 1627, the Emperor Ferdinand II conferred on his general, Count Wallenstein, the title of Generalissimo of the Baltic and Open Seas. The new Generalissimo was already in control of several territories in northern Germany, and by November he had installed himself in the Baltic port of Wismar, where he set to work to build up the imperial navy. In the same month, Gustav Adolf wrote anxiously to his Chancellor Axel Oxenstierna: ‘The popish league comes closer and closer to us. They have by force subjugated a great part of Denmark, whence we must apprehend that they may press on to our borders, if they be not powerfully resisted in good time.’5 The Chancellor agreed. Imperial forces had by now captured the whole of mainland Denmark, and the Danish King had been forced to retreat to his nearby islands. From Denmark an attack might easily be launched against Sweden itself, on its own territory. The situation, Oxenstierna remarked, ‘makes my hair stand on end’.
In January 1628, a secret committee of the Swedish Senate agreed to an invasion of the Emperor’s German lands if the King should deem it necessary. A pre-emptive attack, to draw the imperial forces away from their present too threatening position, had been Gustav Adolf’s own suggestion. In the face of the Habsburg threat, Poland was demoted to a secondary enemy, and Oxenstierna was accordingly dispatched to conclude a peace in the east, so that Swedish forces might be deployed elsewhere. After almost two years of negotiating, and twelve years of war, the Poles agreed to a truce.6 Since their king, Sigismund III, would not renounce his claim to the Swedish throne, a real peace remained elusive, but for Gustav Adolf a halt to the actual fighting was for now just as useful. It was an opportune moment for the Swedes to become involved at last in the great conflict which had been gathering pace in the Habsburg lands for more than a decade already. Protestant Germany had found no champion, and many exiled voices were calling for Swedish help. Now the armistice with Poland released thousands of battle-hardened men, ready for active service elsewhere.
Gustav Adolf’s decision met with loud applause from the Dutch; they had their Baltic trade to protect. But they were not the only power to welcome the idea of a Swedish march against the Empire. The French encouraged it, too, and promised to assist with subsidies; Catholic France was no friend to Catholic Austria, and Richelieu had hopes of using the Swedes as a pawn in his own ongoing game against the Emperor. But his terms were unacceptable to Gustav Adolf, and towards the end of 1629, preferring to find other allies, the King sent his own emissaries to the various courts and free cities of Europe; all returned empty-handed. The German Protestant princes, who had most to gain by a Swedish invasion, also declined to help, for by the same invasion, or so they feared, they also had most to lose.
Sweden was a small country, with not many more than a million souls. Despite many recent reforms initiated by the King and his able Chancellor, it was still poor, with commerce and industry struggling to develop, and the state coffers empty after years of war by land and sea. It could not afford to fight alone against the resourceful Habsburg Empire. Bereft of allies, Gustav Adolf hesitated. Then, paradoxically, the very lack of money which had stayed his hand now forced it. In Prussia, squadrons of German cavalry who had fought for him against the Poles stood waiting; they were mercenaries, and, though their Polish campaign was over, they could not be disbanded, for there was no money to pay them off. If they were kept in service, payment could be delayed, and so it was decided. The cavalry would be sent to Pomerania, now occupied by imperial troops, and there the rest of the Swedish army would join them.
The forces ranged against the Swedes were led by the Czech Count Wallenstein and General Count Tilly, the latter a Dutch nobleman and a professional soldier, a Jesuit manqué whose devotion to the Virgin Mary and strict personal morality had earned him the epithet of ‘the monk in armour’.7 Wallenstein, though he led his own armies, was neither by nature nor by training a military man. Modestly born, through an advantageous marriage and the cheap purchase of no fewer than 66 estates confiscated from the defeated Bohemian rebels a few years before, he had become one of the wealthiest men in Europe. He was consequently able to raise and pay large armies of his own, and owing to his administrative brilliance, to keep them fully supplied as well.8
The imperial forces needed Wallenstein, but at this crucial point, unwisely, they let him go. Flush with recent Catholic victories, in March 1629, the Emperor Ferdinand had declared an Edict of Restitution, whereby Protestant worship was to be banned, and the Catholic powers were to reclaim all lands acquired by Protestants since the Peace of Augsburg in 1555, almost 75 years before. It was an extravagant order which looked, even then, impossible to carry out. The areas in question were huge, and it seemed that there were not even enough potential Catholic landowners to claim them. Many leading Catholics opposed the Edict, among them Wallenstein himself. He had in fact been brought up as a Lutheran, and although in his youth he had converted to Catholicism, the armies he now maintained were full of Protestant soldiers. His protest against the Edict was met by his swift dismissal from the imperial forces, who were now to be commanded by Tilly.
The Emperor’s Catholic allies were delighted. They had resented Wallenstein’s swift climb to power, suspecting that Ferdinand was little more than a pawn in the Count’s ambitious hands. But they were soon to regret his departure, for as he went so too did his men, along with many thousands of other imperial soldiers who had also been paid with his money, and fed, clothed, mounted, and armed through his superbly organized lines of supply. In due course Wallenstein would return, but now, to the Emperor’s dismay, the gap left on the battlefields by the armies of his former ally was filled by those of a new and fearsome enemy, Gustav Adolf, the King of Sweden.
The Swedes pressed inland, and on a hot and windy day in the September of 1631, they drew up at Breitenfeld, near the Saxon city of Leipzig, where imperial forces commanded by Tilly were already waiting. At the eleventh hour, the wavering Elector of Saxony, Johann Georg, had thrown in his lot with the Swedes; his own land was now at stake, and he had arrived to do battle himself at the head of his ranks of young noblemen, with their new-polished armour and their gaily coloured cloaks – ‘a cheerful and beautiful company to see,’ said Gustav Adolf, and so indeed they must have seemed by comparison with his own hardbitten men in their torn and dusty outfits.
Tilly’s forces had begun to fire as soon as their opponents came into sight, but the imperial general, despite his great experience, was soon disconcerted by the novel ‘chessboard’ manoeuvres of the Swedes, whose agile little squares of alternating cavalry and infantry swivelled to fire in all directions, easily outmanoeuvring Tilly’s traditional forward-facing lines.9 Despite a dazzling sun against them, and despite the hasty departure of the frightened Saxon Elector and most of his novice troops, the Swedes achieved a resounding victory, in no small part due to the brilliant planning and indefatigable energy of their own remarkable King.10
And by morning, of the host of imperial soldiers who had survived the battle only to be taken prisoner by the Swedes, many thousands had enlisted in the service of their yesterday’s foe. After the Battle of Breitenfeld, mercenaries from all parts of Europe flocked to the Swedish standard. By 1632, as well as substantial forces in Prussia and the Baltic, on the seas and at home on Swedish territory, Gustav Adolf had some 120,000 men fighting in the German lands. Of his great army, perhaps one-tenth were native Swedes. The remainder, mostly mercenaries, were drawn from east to west: Finns and Germans, Scotsmen, English and Irish, Frenchmen, Dutchmen, Czechs and Poles and Russians, their motives for fighting