He led a school of painters known as the Bande noire or "Nubians" group (for the sombre palette they used, in contrast to the brighter Impressionist and Postimpressionist paintings), and was friends with such artists as Auguste Rodin.

[1] Cottet studied at the École des Beaux-Arts, and under Puvis de Chavannes and Roll, while also attending the Académie Julian (where fellow students formed Les Nabis school of painting, with which he was later associated).

He travelled and painted in Egypt, Italy, and on Lake Geneva, but he made his name with his sombre and gloomy, firmly designed, severe and impressive scenes of life on the Brittany coast.

For the next twenty years he painted scenes of rural and harbor life, portraying a culture Parisians still found exotic.

Cottet was more explicitly the leader of his own small movement, the Bande noire of the 1890s, which included Lucien Simon and André Dauchez, all influenced by the realism and dark colours of Courbet.