Prussian campaign (1626–1629)

Background

Gustavus Adolphus and Swedish leadership remained unsure how Swedish cavalry would perform against the Winged Hussars despite the victory at Wallhof. Danzig was believed to be a launch point for a Commonwealth invasion of Sweden, and Gustavus wanted to move the war into Prussia to pressure Sigismund III. An invasion there would prevent an army being created to invade Sweden and offered more favorable supply lines.

Campaigns

In late June 1626 the Swedish fleet arrived off Pillau. The fortress surrendered after its garrison of 340 could not defend it. Danzig was blockaded by Carl Gyllenhielm, who established a toll. The Swedes captured Elbing, Frauenberg, Braunsberg, Mewe, Marienburg, and Putzig.

Instead of besieging Danzig due to its 5,000-man garrison, the Swedes surrounded it and built fortifications at Dirschau and Gdańsk Head. Stanislaw Koniecpolski formed an army of 4,000 in late July, which grew to 10,000–11,000 by September. Gustavus marched with 2,000 infantry and 1,000–1,200 cavalry. Skirmishes at Warmhof on 22 September, known as the first battle of Mewe, were inconclusive.

The Commonwealth lifted the siege and withdrew. 500 Poles and 30 Swedes died.

Gustavus returned to Stockholm. During winter, Commonwealth attempts to repel Swedes from Gdańsk Head were repelled by Johan Banér, though Koniecpolski recaptured Wormditt and other fortresses. In November 1626 the Kwarciane army under Koniecpolski arrived in Royal Prussia, aiming to remove the Swedish garrison from Puck.

Aftermath

In September 1629 Sweden and the Commonwealth signed the six-year Truce of Altmark, pushed by England, France, and the Dutch Republic. It could be no more than a truce because Sigismund refused to relinquish his claim on the Swedish throne. The Swedes gained de facto control of Livonia north of the Daugava, retained Braunsberg, Elbing, and Frauenberg, and received Pillau, Fischhausen, Lochstädt, and Memel, plus the main share of tolls on Danzig trade.