Battle of Weichselsmünde

The Battle of Weichselsmünde was a surprise attack by Swedish artillery on a Polish fleet stationed outside Danzig at Weichselsmünde in 1628.

Background
On May 15, 1628, Gustavus Adolphus returned to Pillau with reinforcements for the Swedish army, at this point around 12,000 men were in Gustavus' army. He goes to Danziger Haupt, where he awaits Axel Oxenstierna, one of his top advisors. Gustavus wants to invade Lithuania, but Axel advises him not to, stating: "där kommer hans majestät avsides i världen." which roughly translates to: "There his majesty would get secluded from the world."

Battle
On July 15, Gustavus decided on a surprise attack on Danzig, and Gustavus himself led a force of 25 leather cannons, which had excellent mobility. He brought it over a swamp that the Poles deemed impossible to cross. After this, a 6-hour-long battle between the Swedish Army and the Commonwealth fleet began. The Commonwealth fleet suffered heavy casualties, with most ships being heavily damaged and 3 of the Commonwealth's ships being destroyed, including the admiral ship. However, the rest of the fleet managed to retreat back into Danzig, and heavy rain would prevent the fleet from suffering further damage. The Swedes lost 12 soldiers, along with a company commander by the name of Patrick Hume.

Aftermath
Through this action, Gustavus had hoped to force Danzig into signing a treaty of neutrality, but this didn't happen.