As a naval commander he served with distinction in the Adriatic Campaign during World War I. Cras was born and died in Brest.

[2] His daughter, Colette Cras, a concert pianist for whom he wrote his piano concerto, married the Polish-French composer Alexandre Tansman.

It tells the well-known story of the attempt by Polyphemus (baritone) to steal Galatea (soprano) from Acis (tenor).

Albert Samain, the librettist, humanized Polyphemus by having him become aware of the feelings shared by two lovers and thus decide not to crush them.

[2] (A recording of this opera was released in 2003, with Bramwell Tovey conducting the Luxembourg Philharmonic Orchestra and Armand Arapian in the title role.)

Cras's later work developed a more acerbic style comparable to that of Béla Bartók, though formally close to César Franck.

"[4] The Trio for Strings and Piano also blends African and Eastern melodic patterns with Breton musical traditions into a coherent whole.

The critic Michel Fleury compares his work to the Japonist style of the artist Henri Rivière revealing "a stylised Breton land, as though it had been passed through the sieve of his varied experiences gained in the four quarters of the globe.