Background
He was born in Pleubian, Côtes-d"Armor.
He was born in Pleubian, Côtes-d"Armor.
He studied at the small seminary of Tréguier, then at the college of Lannion.
His name is also spelled Erwan Bertou and Yves Berthou. He also used the bardic pseudonyms Kaledvoulc"h, Alc"Houeder Treger and Erwanig. He worked as an engineer in Le Havre, later moving in 1892 to Rochefort.
He joined the Navy for five years.
During his service he visited the Caribbean, Africa and China. Berthou returned to Le Havre in 1896.
He then began contributing to the journals L"Hermine and Revue des provinces de l"Ouest. In 1897, he published a magazine Louisiana Trêve de Dieu (The Truce of God), but it folded after a year.
He continued to work as an engineer, especially in construction of settlements in 1898 in Paris.
In the following year was one of twenty-two Bretons who went to Cardiff to establish links with Welsh neo-Druidism, being received at the Gorsedd. He also joined the Union Régionaliste Bretonne, helping to create the Breton nationalist movement. He participated in all stages of the creation of the Gorsedd of Brittany, of which he was Archdruid from 1903 to 1933, using the bardic name Kaledvoulc"h.
He occasionally participated in Emile Masson"s journal Brug.
In 1906 Berthou and Jean Le Fustec published European to gir of rear Varzed, Triades des druides de Bretagne, a translation into Breton of the 46 theological Triads of the neo-Bards, according to a text first published by Iolo Morganwg with his own Lyric Poems, then in the Barddas of J. William ab Ithel (1862). The collection, in fact a forgery by Morganwg, was claimed to have been a translation of works by Llywelyn Siôn detailing the history of the Welsh bardic system from its ancient origins to the present day.
He found it difficult to keep it solvent, and was reduced to great poverty a result of the inflation after the war. His last years were severely impoverished, leading to his wife"s mental breakdown.
Members of the Breton national movement organised financial assistance for him.