Free imperial city
The evolution of some German cities into self-ruling constitutional entities of the Empire was slower than that of the secular and ecclesiastical princes. In the course of the 13th and 14th centuries, some cities were promoted by the emperor to the status of Imperial Cities (Reichsstädte; Urbes imperiales), essentially for fiscal reasons. Those cities, which had been founded by the German kings and emperors in the 10th through 13th centuries and had initially been administered by royal/imperial stewards (
The Free Cities (Freie Städte; Urbes liberae) were those, such as
Over time, the difference between Imperial Cities and Free Cities became increasingly blurred, so that they became collectively known as "Free Imperial Cities", or "Free and Imperial Cities", and by the late 15th century many cities included both "Free" and "Imperial" in their name.
 Like the other Imperial Estates, they could wage war, make peace, and control their own trade, and they permitted little interference from outside. In the later Middle Ages, a number of Free Cities formed City Leagues (Städtebünde), such as the
In the course of the Middle Ages, cities gained, and sometimes — if rarely — lost, their freedom through the vicissitudes of power politics. Some favored cities gained a charter by gift. Others purchased one from a prince in need of funds. Some won it by force of arms during the troubled 13th and 14th centuries and others lost their privileges during the same period by the same way. Some cities became free through the void created by the extinction of dominant families, like the Swabian
A few, like Protestant