Born in
Liège, he was the son of organist
Emile Jean Joseph Dethier (1849-1933), the brother of violinist
Edouard Dethier, and the uncle of physiologist
Vincent Dethier. He studied at the
Royal Conservatory in his native city with
Alexandre Guilmant. He was awarded
premiers prix in organ, piano, harmony, and fugue from the conservatory. In 1886, at just 11 years of age, Dethier was appointed organist at the
Église Saint-Jacques-le-Mineur de Liège. He eventually left there to work in the same capacity at the
Église Saint-Christophe de Liège. == Relocation to United States ==