This paper examines the transfer of bishops in the Frankish kingdom due to the Viking invasions during the second half of the ninth century. The most comprehensive case — that of Actard of Nantes — provides sufficient information on the situation of the prelate and especially how it was presented by the secular and ecclesiastical authorities of the time. The change in the position of Hincmar Archbishop of Rheims on this issue, in 872, reveals the political and canonical stakes that could dress such cases. In light of this and other examples known at the end of the ninth century one can wonder whether infestatio paganorum was not primarily an argument to justify transfers that intervened on partisan grounds.