 Before World War II, Weisgerber established links with Celtic nationalists in Ireland, Britain and Brittany, which were seen as a threat to national unity by the respective majority governments (the British Crown and the Centralist French Republic).The Breton nationalists joined Germany at the beginning of the war, at least some of them.After the Fall of France, Weisgerber initiated the creation of the and directed the radio station "Radio Rennes Bretagne" (Radio Rennes of Brittany) which broadcast the first radio transmissions in the Breton language, something that most Bretons had been waiting for unsuccessfully for decades.