Frederick William, the “Great Elector”.
As Frederick William finally took possession of East Pomerania, his interest in the Baltic intensified. In 1654 Queen Christina of Sweden abdicated in favour of her cousin, Charles X. The new king showed every sign of emulating Gustavus Adolphus in his desire to make the Baltic a Swedish lake. The Elector was alerted to the prospect of another war between Sweden and Poland when Charles approached him with a demand for the towns of Pillau and Memel as the price of a Swedish-Brandenburg alliance (1654). Frederick William was reluctant to make quick concessions even to gain a powerful ally. He was wary of being drawn into another conflict which might result in the loss of his hard-won Westphalian gains; but more to the point, his instinct was to secure the maximum advantage from the situation by selling his military support to the highest bidder. Meanwhile, to protect his own position he turned to the Dutch Republic, whose vital trading interests would also be affected by Swedish occupation of the Baltic ports. A defensive treaty was concluded at The Hague in 1655, by which the Elector hoped to retain his independence.
However, within a matter of weeks Sweden’s armies swept across the plains of Poland, capturing all the leading cities. They then wheeled round against Polish Prussia, and after taking all the towns except Danzig, moved on to the duchy of Prussia. Backed into a corner at Königsberg, the Elector avoided battle to save his army and accepted the Swedish terms (1656). Charles X appeared to have brought Brandenburg-Prussia to heel. Ducal Prussia became a Swedish fief and Frederick William promised military and financial aid to his overlord, and the use of Pillau and Memel, along with half the port dues. As a modest reward to his new vassal, Charles allowed Frederick William to take the bishopric of Ermland, an enclave within East Prussia.
The Treaty of Königsberg (1656) exemplified the Elector’s dilemma. Armed neutrality was an obvious strategy for a second-class state, but there would be situations in which the ruler would be forced to take sides. By arming his state in order to sell its military capacity, he had to ask himself whether it was better to take the initiative and negotiate with the superior power in the hope of winning an ally’s prize. Or was it wiser to support the weaker of two major powers in the expectation that the aggressor would eventually be defeated by a hostile coalition? Over the years Frederick William turned to both these strategies and switched from one alliance to another. If he was flexible and inconsistent in his diplomatic and military strategies, he was unwavering in his overall objective, which was to enhance his possessions and the status of the dynasty he embodied. This impelled him to take every possible step to defend and consolidate his patrimony.
Later in 1656, as the Poles recovered much of their lost ground, the Elector found himself courted by both sides. But it was too early to desert Sweden, which still appeared the dominant power. In return for a promise of territorial booty in the west of Poland, he agreed by the Treaty of Marienburg (1656) to fight alongside the Swedes. Leading his army of 8,500 troops, Frederick William joined in the three-day battle of Warsaw, where he proved his military prowess. The victory caused Sweden’s enemies to reform. The Dutch fleet came to the defence of Danzig, the Russians took Ingria and Livonia and Ferdinand III sent help to John Casimir, the Polish king. Frederick William saw his chance to turn the diplomatic tables on his ally, Sweden. He had also clarified his war aims, for the war had already shown how elusive territorial gains and promises could be. But there was an important constitutional matter to be rectified: the Elector wanted to be freed permanently from Swedish and Polish suzerainty. In the Treaty of Labiau (1656) Charles X agreed to this demand and recognized Frederick William as the sovereign ruler of ducal Prussia. In addition, Sweden surrendered her claims to the customs dues levied in Prussian ports. With these concessions secured, a small Brandenburg force joined in Charles’s latest campaign against Poland (1657).
The hostilities in Poland, however, turned into an inconclusive guerilla campaign. When Denmark declared war against Sweden and Charles X decided to decamp from the mainland to concentrate on fighting his oldest enemy, Brandenburg returned to a state of armed neutrality. To conserve his army, Frederick William withdrew circumspectly into Prussia (1657). Sweden was now on the defensive against a coalition of powers and Frederick William no longer felt the need for the Swedish alliance. Charles X’s departure and Poland’s relative weakness gave him an opportunity to make further political capital. He expressed his readiness to come to terms with the Poles on the key condition which he had won from the Swedes at Labiau: recognition of his sovereignty in Prussia. As it happened, the Emperor had his own dynastic reasons for wanting to detach Brandenburg from the Swedish alliance. In the ensuing negotiations he put pressure on the Polish king to match the Swedish bid and accept Frederick William’s sovereign rights over ducal Prussia. In the Treaty of Wehlau (1657) John Casimir reluctantly made this substantial concession, and in return Brandenburg returned Ermland to Poland. Frederick William followed this triumph with a total turnabout when he agreed terms with the Austrian Emperor and the King of Denmark.
By 1658 the Nordic War was in its last phase. The fighting had concentrated on Denmark, where the spectacular gains made by Charles X in 1657 were partly countered by the armies of the anti-Swedish coalition, to which Frederick William contributed a Brandenburg force. The possibility of territorial gains at Sweden’s expense now opened up. At the head of 30,000 men, the Elector drove the Swedes from Schleswig and Holstein (1658) before turning his attention to Swedish Pomerania and the ports of Stralsund and Stettin in particular. Although Stettin withstood his attacks, by the end of 1659 Brandenburg forces were in control of most of Pomerania. In the event of peace, the Elector’s bargaining position against Sweden looked stronger than it had ever been. His main goal was Swedish Pomerania, which he had failed to achieve at Westphalia.
It was the intervention of another superior power which blocked Frederick William’s strategy. The French minister, Mazarin, was reluctant to see Sweden lose her prime position in the Baltic. Brandenburg’s allies in the anti-Swedish coalition- Poland, Denmark and the Austrian Emperor-had grown weary of the war, despite the fact that Sweden’s position was suddenly weakened by the death of Charles X (1660) and the advent of a regency for his 4-year-old son. However, Frederick William learned again the harsh reality of politics, that a second-rate power is unwise to abandon neutrality and fight alone. At the Peace of Oliva (1660) the Elector’s recent allies had no reason to support him against French diplomacy, which carried the day. He had to accept a compromise. He secured his first war aim, the recognition by all the signatories that he was the sovereign Duke of Prussia. But to his deep disappointment he had to withdraw his army from western Pomerania and accept Sweden’s possession of the Baltic province.