[POTN] 3.14 - Treaty of Potsdam

While Karl's siege of Berlin lingered on, the situation in the Baltic was not looking well for the Swedes. Despite the steady frontline in Scania, the Swedish Navy was entirely unable to defeat Niels Juel's fleets, suffering defeat after defeat.

After a prolonged campaign, the Danes successfully occupied the island of Gotland in late October, 1668, retaking the island from Swedish hands for the first time since 1645. An attempted invasion of Öland soon followed. While the Swedes, taking advantage of the cold weather, did achieve a tactical victory, Swedish lost far more vessels than the Danes and became practically paralysed in the Baltic.

Seeing the naval defeat, King Gustav and the Riksdag wished to prioritise evicting the Danes from Scania. Nonetheless, without sufficient naval support, this operation became far harder than what it once was. The panic brought to Stockholm by the naval defeats also meant that the King had no choice but to spend a considerable effort to keep the capital orderly, primarily utilising his royal guards. Similar situations in other cities meant the number of well-trained soldiers the Swedes could field decreased further.

A smaller Swedish naval force still functioned on the southern coast of the Baltic, simply because the Danes saw no reason not to prioritise attacking Swedish proper first. Prince Karl gave the absolute order that these forces should stay where they were, instead of sailing north for suicide missions.

Meanwhile, Prince Karl maintained the pressure outside Berlin. The Elector of Brandenburg attempted to negotiate with preconditions many times, which were all rejected by Karl, who demanded an unconditional surrender. A famine began throughout occupied Brandenburg as winter befell in early November, 1668. The Swedes' looting caused many rural Brandenburgers to suffer immensely from starvation and lack of basic resources.

Officially, Karl called for his army to "be respectful" to the "Protestant brothers and sisters" on Bradenburger soil. Nonetheless, Karl almost never enforced discipline, leaving plundering and looting, among other crimes, extremely common. The city of Berlin itself suffered even more from endless bombarding by Karl's army. The city walls were breached several times, but the Elector somehow managed to fill the gaps with soldiers every time, defending the city with the last drop of Brandenburger blood.

The Elector's network throughout the Empire, meanwhile, sought to hire more mercenaries to help with the defense of the city. Yet, financial resources were draining, and the Elector could only raise taxes on the regions that Karl's army had not yet invaded. This, like expected, angered the people of Ducal Prussia. Just a few years prior, in 1661, the Prussian Estates in Königsberg already attempted a rebellion against the fiscal centralisation policies forced by Friedrich Wilhelm. That ended with the Elector leading his soldiers into Königsberg in 1662, cracking down with violence, and arresting the local leaders.

A local noble of Königsberg, Christian Ludwig von Kalckstein, from a family that had long been critical of Friedrich Wilhelm, was accused of attempting to assassinate the Elector back in 1667. He, when arrested, had to beg for mercy from the Elector in early 1668, but had remained bitter ever since.

With the anger of the citizens of Königsberg again provoked by the Elector, Kalckstein took the chance. On 3rd December, he rallied the dissents in the region, and through territories of Poland and Saxony, sent to Karl letter signed by many nobles in the city, pledging loyalty in exchange of freedom from Berlin. Karl, receiving the letter later that month, accepted the pledge of loyal on Swedish behalf. He intentionally left the status of Prussia unsettled, wishing to first eliminate the Brandenburger threat before going back to Stockholm to talk about the issue with King Gustav.

In Sweden, the situation remained dire. The endless naval defeats meant communication with the Eastern Finnish provinces was often disrupted, especially as the northern land route became rather perilous in the coldest months of the year. After months of failing to evict the Danes from Scania, the command in Stockholm had no choice but to shift their tactics, aiming to restore naval superiority.

While the Swedes, after paying massive efforts, did manage to restore some naval control near the shores, it came with a large cost. Countless Swedish vessels were totally destroyed by superior Danish naval fleets, and most of the Danish withdrawals were conducted in an orderly way as strategic decisions rather than chaotic retreats. The warfare in Scania slowed down during the winter. The harsh weather meant it was impossible for either side to conduct large-scale offensives, and thus both the Swedes and the Danes spent most of the winter fortifying their own defensive positions.

It was in February 1669 that Johann Georg II had his Saxon armies march into the Brandenburger city of Cottbus. For decades, Cottbus had been a Hohenzollern enclave buried deep inside Saxon territories, far away from the centre of Brandenburg. Johann Georg marched into the city by claiming to "protect the Protestants in the city from mismanagement and starvation". While it was apparent that Saxony had long held ambition on the city, Berlin had no way to retaliate at that point, and Sweden almost immediately recognised the annexation after receiving the news.

The Siege of Berlin would drag on for months longer. Despite almost impossible odds, the Elector refused to surrender to Karl, believing Karl's terms were utterly unacceptable. The constant failure to breach the walls of Berlin definitively caused Swedish brutality against the Brandenburgers in the occupied regions intensified further.

As the famine in Berlin worsened, the Elector was under greater and greater pressure to surrender. The fact that the Duchy of Prussia was no longer obeying him meant the Elector's taxation income also decreased severely, leading to a lack of mercenary support. Yet, Karl was also under the pressure to achieve peace as soon as possible. The financial resources of the Swedish military was draining - while Karl could definitely force the army to keep the pressure, he must also take into account of the fact that Sweden was unable to defeat Denmark and winning Sweden the war was the primary goal, rather than simply devastating Brandenburg.

Meanwhile, back in Sweden, the Swedish Navy attempted another round of attack in March. The Danes retreated slightly, but still inflicted far more damage on the Swedes than the damage they themselves suffered. King Gustav was tired of the naval incompetence, but could offer no cure. The Admirals constantly complained about a lack of capitals, and Gustav was in no position to generously increase funds for the Navy, with his own national treasury already drained by the war.

It was in late April that the Elector and Karl finally established stable contact. With the mainland forces not gaining any ground, Karl felt increasingly urgent to deal Denmark a fatal blow, and thus became more willing to negotiate with the Elector. The Elector would only negotiate given that Karl would agree to keep the Electorate of Brandenburg largely territorially intact. Karl initially was hesitant to grant the request, but geopolitical reality meant he agreed with the condition in early May anyway.

Friedrich Wilhelm and Karl agreed on a preliminary peace treaty in late May, and Karl immediately sent it to Stockholm for Gustav's approval.

Gustav, totally overwhelmed by the stalemate against Denmark, was more than willing to have Karl's elite army back in the picture, and thus signed the preliminary treaty immediately, sending it back to where Karl was.

On 19th June, 1669, Sweden and Brandenburg-Prussia officially signed the Treaty of Potsdam, concluding the following:

1) The Kingdom of Sweden and the Electorate of Brandenburg shall cease all hostilities. Both nations shall henceforth treat each other as fellow Protestant brothers, advocating for each other's interests.

2) The Elector of Brandenburg forfeits all rights and ownerships in the Duchy of Prussia. The total transfer of the territory to Swedish sovereignty shall be recognised by the Elector.

3) Minor border adjustments for the Electorate of Brandenburg, including a northeastern strip of territory to be incorporated into Swedish Pomerania, and the enclave of Cottbus to be annexed by the Electorate of Saxony.

4) The Secret Accords of Odense shall immediately be declared null and void. The Electorate of Brandenburg shall henceforth hold no military obligation towards the Kingdom of Denmark.

5) The Electorate of Brandenburg shall be allowed to maintain the port of Wismar for transportation into the Baltic. The Electorate of Brandenburg shall repay the two million thalers paid by Sweden following the Peace of Westphalia in 1648, in order to cover the occupation costs of the Swedish army in the past year.

The peace treaty, nonetheless. was not received well by either France, the Dutch Republic, or the Austrian Habsburgs. Both Paris and Vienna were worried that a Swedish annexation of Prussia would cause Sweden to become the undisputed dictator of Baltic, while the Dutch were worried about trade being disrupted.

Facing another string of naval defeats, Gustav was unwilling to provoke the anger of even more powers. Vienna especially put lots of pressure on Stockholm, forcing Gustav to "embrace a more noble settlement".

On 17th July, Gustav eventually yielded, and had the Riksdag pass the "Act of Prussian Fiefdom". Gustav publicly announced the Act on the next day, 18th July, calming the foreign powers. The Act made the Duchy of Prussia an autonomous Swedish fiefdom, with loyalty to both the Duke and the King of Sweden. Yet, Sweden was barred from exercising administrative power in the Duchy. Prince Karl Gustav, Duke of Öland, was appointed by Gustav as Karl I Gustav, Duke of Prussia, and the Duchy shall be inherited by his son and future descendents at his passing.

The appointment was well-received by Karl, who was regrouping his army in Brandenburg. It was his 13-year-old son, also named Karl, who would travel to Königsberg with Swedish generals to receive blessing as Hereditary Prince by the Prussian Estates.

Friedrich Wilhelm was furious at the fact that his conqueror had stolen his title of "Duke of Prussia", but was unable to muster any strength to fight Karl anymore. Most of the Electorate of Brandenburg were mostly compliant as Karl slowly regrouped and retreated back into Swedish Pomerania to prepare for the coming operations.