He wrote about the Spanish Civil War and a number of biographies, including lives of Saint Cyran and Lope de Aguirre, a 16th-century Basque conquistador active in South America.
He was educated by French nuns at the Notre Dame school in Azpeitia and then by the Marist Brothers, where he made a friend for life, Inazio Eizmendi Manterola, who also became a writer.
He soon befriended José de Ariztimuño, a priest who supported Basque literature, later shot by rebels in 1936, and José María Benegas Echeverría, a lawyer and a member of the Basque Nationalist Party (PNV) who fled to Venezuela at the time of the civil war.
He joined the PNV before 1935, but was a staunch Roman Catholic, and his wife was expecting a fourth child when the civil war broke out, two factors which together made up his mind not to enlist in the Basque nationalist cause as a defender of the Second Spanish Republic.
[2] At the end of the war, Arteche settled in Zarautz, and then in 1949 he moved to San Sebastián to take up an appointment as an archivist.