During the occupation of France, Mordrel and others were involved in setting up collaborationist ventures. 1942 saw the birth of the Institut celtique, absorbing members of Seiz Breur and a diverse range of Bretons. In the meantime, a manifesto signed by the Seiz Breur announcing the role of Brittany in post-war Europe appeared in "La Bretagne", a newspaper edited by Yann Fouéré. This text reminded readers of the lesson in "racial vitality" they gave at the International Exhibition in 1937. Political disputes involving the war and nationalist controversies led to the union's closure in 1944. Like much of the Breton movement, at the end of the war the group collapsed amid accusations of collaboration.