The battle of Stångebro was the decisive encounter of the Swedish Civil War of 1597-1598 between Sigismund III, king of Poland-Lithuania and Sweden and his uncle Charles, duke of Södermanland. Sigismund was a largely absentee monarch, spending most of his time in Poland, leaving Charles as his regent. Sigismund’s Catholicism also made him unpopular in Lutheran Sweden. Civil War broke out in 1597. Sigismund responded by invading Sweden at the head of a small force of German and Hungarian mercenaries. He did not receive a great deal of support in Sweden, and his final army only reached a strength of 7,000 men.
This army won the first battle of the invasion, at Stegeborg, on 8/18 September, but Sigismund allowed Charles to escape with his army largely intact. Two weeks later the combatants came together again at Stångebro. Charles offered peace talks. Sigismund accepted, and began to withdraw his army back to its camps. Charles then attacked. In misty weather Sigismund’s army was caught by surprise. Many of his Swedish supporters then refused to fight their fellow countrymen. Sigismund’s mercenaries attempted to fight on, but were eventually defeated.
His victory at Stångebro left Charles effectively in charge in Sweden. Sigismund returned to Poland late in 1598, and was officially deposed as king of Sweden in 1599. The alliance between Sweden and Poland-Lithuania that Sigismund’s election as king of Poland-Lithuania was intended to reinforce collapsed, and a period of hostility between the two states soon followed, with the first Swedish-Polish war breaking out in 1600.