The decline of the town started in the 1520s, when the humanist school lost its former influence. The troubles surrounding the Protestant Reformation brought instability and unrest to the region. The town experienced the German Peasants' War in 1525 and its convents were sacked by a mob in 1534. During the same period Sélestat lost its pre-eminence in the Decapolis because the city of Mulhouse left the alliance in 1515 and was replaced by Landau in 1521, moving the geographical centre of the alliance to the north.