At about this time the surrounding areas experienced recurring fragmentation and reincorporations among a number of feudal secular and ecclesiastical lordships, a common process in the Holy Roman Empire. Alsace experienced great prosperity during the 12th and 13th centuries under Hohenstaufen emperors. Frederick I set up Alsace as a province (a procuratio, not a provincia) to be ruled by ministeriales, a non-noble class of civil servants. The idea was that such men would be more tractable and less likely to alienate the fief from the crown out of their own greed. The province had a single provincial court (Landgericht) and a central administration with its seat at Hagenau. Frederick II designated the Bishop of Strasbourg to administer Alsace, but the authority of the bishop was challenged by Count Rudolf of Habsburg, who received his rights from Frederick II's son Conrad IV. Strasbourg began to grow to become the most populous and commercially important town in the region. In 1262, after a long struggle with the ruling bishops, its citizens gained the status of free imperial city. A stop on the Paris-Vienna-Orient trade route, as well as a port on the Rhine route linking southern Germany and Switzerland to the Netherlands, England and Scandinavia, it became the political and economic center of the region. Cities such as Colmar and Hagenau also began to grow in economic importance and gained a kind of autonomy within the "Decapole" or "Dekapolis", a federation of ten free towns.