At its congress on April 11, 1931, the Breton Autonomist Party broke up under the differences between the federalist and nationalist factions.
Faced with the formation of the separatist Breton National Party, the federalists Maurice Duhamel, Morvan Marchal, Yann-Morvan Gefflot, Goulven Mazéas, René-Yves Creston and others, founded the Breton Federalist League.
In the first issue of this journal, Goulven Mazéas wrote: the truth is that our Masters rip apart piece by piece our sense of who we are in order to fill us with a burning love for an alleged fatherland [France], a patriotic cloak already adopted by those who ignore their motherland... we perhaps disavowed an effective nationality to adopt a fictitious nationality to which our blood, our race are completely foreign.
It was dissolved in 1934 to be replaced by the Breton Federalist Movement which was joined by Morvan Marchal, Gestalen, Francis Bayer du Kern, Goulven Mazéas and Rafig Tullou.
Members also founded the neo-Pagan Druidic group Kredenn Geltiek Hollvedel.