The Décapole (French pronunciation: [dekapɔl] ⓘ; German: Zehnstädtebund [ˈtseːnʃtɛːtəˌbʊnt], Dekapolis or Dekapole) was an alliance formed in 1354 by ten Imperial cities of the Holy Roman Empire in the Alsace region to maintain their rights.
In 1354 Emperor Charles IV of Luxembourg ratified the treaty uniting the towns of Haguenau, Colmar, Wissembourg, Turckheim, Obernai, Kaysersberg, Rosheim, Munster, Sélestat and Mulhouse.
[1] Hagenau became its capital while the Imperial city of Strasbourg, though venue of the league's diets, remained outside the alliance.
[1] The alliance was strongly shaken by the Thirty Years' War which ravaged the region, allowing Louis XIV of France to conquer the cities according to the 1648 Peace of Westphalia.
Mulhouse remained an independent city and exclave of the Swiss Confederation until in 1798 it was annexed to the French First Republic.