The Pope's increasing authority in the middle of the 11th century led to a change in the relative status of the liturgical feasts that were celebrated in various European dioceses. From the second half of the 11th to the 14th centuries there was a disagreement between those who, according to the Roman custom, considered that the celebration of the Whitsun octave prevailed and those who stood up for the celebration of the Trinity Sunday octave. In order to give each of these feasts its proper solemnity some dioceses in the Holy Empire swapped Trinity Sunday and the Sunday of its octave celebration. The Liege diocese was one of them. Such permutation, which often went unnoticed, was a frequent source of uncertainty about dates, notably about the original date of Corpus Christi.
