Battle of Prostken

Date	October 8, 1656
Location	Prostken, Duchy of Prussia (present–day Prostki, Ełk County, Poland)
Result	Decisive Polish–Lithuanian–Tatar victory

Belligerents

Commanders and leaders

Subhan Ghazi Agha

Strength

4,000
9 artillery pieces

8,000

Casualties and losses

1,500 killed and captured Swedes
Brandenburgers losses are unknown
9 artillery pieces

200-250 killed and wounded

The Battle of ProstkI was fought near Prostki (German: Prostken), Duchy of Prussia (today in Ełk County, Poland) on October 8, 1656 between forces of the Polish-Lithuanian Commonwealth and allied Crimean Tatars commanded by hetman Wincenty Gosiewski on one side, and on the other allied Swedish and Brandenburg forces commanded by Prince Georg Friedrich of Waldeck, reinforced by cavalry of Prince Bogusław Radziwiłł. The Commonwealth forces won the battle, annihilating enemy forces and taking Radziwiłł captive.

In the late summer of 1656, Swedish and Brandenburgian armies left Warsaw, retreating towards northwest. Polish-Lithuanian commanders decided then to invade the Duchy of Prussia, which had been a vassal state to Kingdom of Poland, and which, as Brandenburg-Prussia, had been an ally of the Swedish Empire (see Treaty of Königsberg (1656). The objective of the invasion was to make “The Great Elector”, Frederick Wilhelm, end the alliance with Sweden.