Le Sidaner’s art evolved out of the Symbolist generation in the 1880s. The beneficiary of sponsorship money from the Dunkerque municipality, Le Sidaner studied at the Ecole des Beaux Arts, under Alexandre Cabanel who was renowned for his severe and uncompromising attitude towards Modern painting.

During the 1890s he made friends with Ernest Laurent and Edmond Aman-Jean, who were old companions of Seurat and the Belgian artist of Les XX, Emile Claus. However the closest friendship he had with any artist was with Henri Martin. It was a friendship that marked the end of his first stylistic period which owed much to Symbolism and the beginning of his explorations with the Divisionist technique.

Pastel was one of his favourite mediums and suited his manner of working. He often exhibited works at the annual Salon des Pastellistes at the gallery of Georges Petit, together with the other Intimistes Martin, Laurent and Aman Jean.

Following the war Le Sidaner remained faithful to his own personal values despite the explosion of Cubism and Expressionism in France. In May 1923, Le Sidaner went to Le Croisic, near La Baule and St Nazaire, on the North East coast of France. Here he made 11 paintings, in which he took great joy noting the reflections of the sun on the facades of the buildings and along the quayside. These Breton canvases were exhibited alongside those of his friends, Henri Martin, Ernest Laurent, in the spacious galleries of Georges Petit.