He participated in the Quimper Pan-Celtic Congress of 1924, with François Debeauvais, Yann Sohier, Jakez Riou, Abeozen, and Marcel Guieysse, under the banner of Breiz Atao.
He later worked for Gwalarn, the literary magazine founded in 1922 by Roparz Hemon and Olier Mordrel, where he established himself by publishing Breton translations from Spanish (Calderon) and ancient Greek (Aeschylus).
He also published his own poetry, notably Nozvez arkus e beg an enezenn (Night Watch at the Edge of the Island), written in memory of Jakez Riou in 1938.
During World War II, Drezen regularly published articles in the Nationalist periodical L'Heure Bretonne, an organ of the Breton National Party.
He also wrote for Mordrel's Stur, Galv (edited by Henri Le Helloco) and in Yann Fouéré's La Bretagne.
In 1941, he published the first full-length novel in Breton, Itron Varia Garmez, which was about the lives of ordinary people in Pont-l'Abbé during the Great Depression (French edition, Denoël, 1943, as Notre-Dame Bigoudenn).