At the outbreak of World War II, he was interned as a German citizen and sent to an internment camp near Aix-en-Provence for 14 months. During this period, Wols concentrated on painting and ink drawings similar to those he started producing upon his arrival in Paris in 1932. In 1940, he was released and settled near Marseilles in Dieulefit and Cassis. Although he lived in poverty during his time in the South of France, with the help of Henri-Pierre Roche he was able to draw and paint in watercolor and sold several pieces. In 1942, an exhibition of watercolors by Wols was held at Betty Parsons Gallery in New York. Again he was forced to flee from the Germans in 1942 which landed him in Montelimar. He spent most of the war trying to emigrate to America, but this proved to be an unsuccessful and costly enterprise.

After World War II ended, Wols started to gain recognition. Upon his return to Paris in 1945, the artist had his first exhibition at the Galerie René Drouin of the watercolors he painted while in hiding throughout the war. This first showing of his work was not very successful. In 1946, he started to paint in oils which resulted in some of his most important works. In 1947, a second exhibition at Galerie René Drouin was a tremendous success. Wols earned the praise of artists such as Mireille Matthieu and critics such as Michel Tapie, who coined the term “Un Art Autre”.

Among his many friends and acquaintances in the artistic community of Paris were luminaries of the period such as Max Ernst, Fernand Leger, Alberto Giacometti, Jean Arp, Jacques Prevert, Simone de Beauvoir, Joan Miro, Alexander Calder, Tristan Tzara and Jean-Paul Sartre. These friendships sparked a keen interest in Existential philosophy which can be seen in his work. He became one of the pioneers of a move away from geometric abstraction towards a more painterly approach to art. Wols was one of the most influential artists of the Tachism movement (also known as Art Informal, Lyrical Abstraction and Matter Painting), which was the European counterpart of abstract expressionism in America. He produced a rich oeuvre which he refers to as ‘Zirkus Wols’. It was inspired by the Surrealist psychic automatism.

In addition, Wols was greatly influenced by the writings of the Chinese Daoist philosopher Laozi. The artist even wrote poems and aphorisms that expressed his aesthetic and philosophical ideas. The friendships of Wols with several well known writers of this period lead to a long series of book illustrations: Visages and Nourritures by Jean-Paul Sartre (1948); L’invite des morts by Franz Kafka (1948); Poemes chinois by Jean Paulhan (1948); Naturelles by Rene de Solier (1948); Baleine-ville by Camille Bryen (1949); and Le Theatre de Seraphin by Antonin Artaud (1950).