What happened at the Battle of Warsaw in 1656?

The Battle of Warsaw in 1656 was a three-day engagement during the First Northern War that served as a critical "test of fire" for the army of Frederick William, Elector of Brandenburg.12

In July 1656, a joint force of 18,000 Swedish and Brandenburg troops, commanded by King Charles X Gustav and Frederick William, faced a larger Polish-Lithuanian army of approximately 40,000 led by King John II Casimir Vasa. After an unsuccessful frontal assault on July 28, the Swedish-Brandenburg forces bypassed the Polish lines on July 29 by maneuvering through a forest to outflank their opponents.1

Despite a Hussar charge by the Polish-Lithuanian forces, the position became untenable, forcing John Casimir to withdraw across the Vistula that night. On July 30, the Swedish-Brandenburg army attacked the retreating Polish forces, securing a victory that led to the Swedish king granting Frederick William full sovereignty over the Duchy of Prussia.12