Background
He was the grandson of a Chouan officer.
He was the grandson of a Chouan officer.
He later adopted the neo-Bardic name Kammermor. He is also known as Kamil Ar Merser 'Erm, the Breton language form of his name. He was based in Paris when in 1909 he published his first collections of poetry.
His proposals caused a sensation. Le Mercier d'Erm also founded the activist journal Breiz Dishual (Free Brittany). The party and journal folded in 1914 on the outbreak of World War I. Immediately after the war, Le Mercier d'Erm helped to found a replacement journal, Breiz Atao (Brittany Forever), which was created in.
He also continued to play a leading role among young Breton nationalist activists between the wars. He launched the newspaper La Bretagne libertaire in 1921, with the article "La Nation bretonne et l’Internationale" (The Breton nation and the Internationale).
His work as a poet and historian is marked by nationalist claims and calls to rebellion against the French state on the model of Irish nationalism. The same year, in the Revue de l’Ouest, he wrote "Traditionalism and separatism", an article advocating separatist politics in defence of cultural tradition. He was the principal founder of the Breton Nationalist Party in 1911, and was arrested when the party launched a protest in the same year at the official opening of a monument to the unity of Brittany and France.
In 1941 on the occasion of the thirtieth anniversary of the Breton Nationalist Party, the newly formed Breton National Party (a different organisation) organised a heartfelt tribute to Le Mercier d'Erm, as a pioneer of Breton nationalism.