This article intends to support the thesis that the eleventh-century investiture controversy was preceded by a similar struggle between Church and State in the Carolingian era. In the ninth century already, some bishops, convinced by a theological principle, stood up for the unity of Christianity and within this constellation for the superiority of episcopal power. At the deposition and public penance of Louis the Pious in 833, such considerations played a very important part. The growth of this episcopal self-awareness is indicated by the slowly evolving interpretation of episcopal responsibility (ministerium) in the Frankish secular and ecclesiastical legislation from the sixth to the ninth century. The disagreement among the Carolingian episcopate about the legitimacy of Louis' deposition, however, resulted in a stalemate during which the former emperor regained control.