Swabian League, association of Swabian cities and other powers in SW Germany for the protection of trade and for regional peace. The Swabian League of 1488–1534 is the best known of the long series dating from the 14th cent. Supported by the Holy Roman emperor as an instrument of imperial power, it comprised more than 26 cities and many nobles, knights, and prelates. The league had a court, a powerful army, and a formal constitution (renewed in 1496, 1500, 1512, and 1522). It backed the election (1519) of Holy Roman Emperor Charles V, and it used its military power to expel Duke Ulrich I from Württemberg. The league played a leading role in putting down the knights' revolt led by Franz von Sickingen, and it helped defeat the peasants in the Peasants' War. The dissolution (1534) of the league resulted from the opposition of interests between its feudal members and its cities and from the religious split caused by the Reformation. Many Protestant members in 1531 joined the Schmalkaldic League. Later attempts by Charles V to restore the Swabian League failed.