was a 20th-century French composer and career naval officer. His musical compositions were inspired by his native Brittany, his travels to Africa, and most of all, by his sea voyages. As a naval commander he served with distinction in the Adriatic Campaign during World War I.
Cras was born and died in Brest. His father was naval medical officer. He was accepted into the navy at the age of seventeen. As a midshipman cadet on the Iphigénie, he travelled in the Americas, the West Indies and Senegal. He was promoted to Lieutenant in 1908. His mathematical skills led to his proposing a number of innovations in technical practices which were adopted by the navy, including his invention of an electrical selector and a navigational plotter protractor known as Règle Cras [fr] (aka Cras ruler, Cras protractor, Cras plotter). (However, it was difficult to operate by some, which inspired the later development of the Breton plotter by Yvonnick Gueret.)
With the outbreak of war in 1914 Cras was appointed as adjutant to Admiral Augustin Boué de Lapeyrère. He later worked in the Submarine Defense Service. In 1916 he was appointed commander of the torpedo boat Commandant Bory. During the Adriatic campaign he sank a submarine and was commended for his bravery in rescuing a sailor who had fallen overboard.
After the war Cras became Chief Secretary to the Chief of General Staff, and was promoted to Commander. He served on several other vessels before being appointed Service Chief on the General Staff for Scientific Research. In 1931 he was appointed Major General of the Port of Brest and promoted to rear admiral. He occupied this position when he died after a short illness.
His daughter, Colette Cras, a concert pianist for whom he wrote his piano concerto, married the Polish-French composer Alexandre Tansman.
