Literary career During the war Camus joined the French Resistance cell Combat, which published an underground newspaper of the same name. This group worked against the Nazis, and in it Camus assumed the nom de guerre Beauchard. Camus became the paper's editor in 1943. He first met Sartre at the dress rehearsal of Sartre's play, The Flies, in June 1943. When the Ailies liberated Paris in August 1944, Camus witnessed and reported the last of the fighting. Soon after the event on 6 August 1945, he was one of the few French editors to publicly express opposition and disgust to the United States' dropping the atomic bomb in Hiroshima. He resigned from Combat in 1947 when it became a commercial paper. After the war, Camus began frequenting the Cafe de Flore on the Boulevard Saint-Germain in Paris with Sartre and others. He also toured the United States to lecture about French thought. Although he leaned left, politically, his strong criticisms of Communist doctrine did not win him any friends in the Communist parties and eventually alienated Sartre. In 1949, his tuberculosis returned, whereupon he lived in seclusion for two years. In 1951, he published The Rebel, a philosophical analysis of rebellion and revolution which expressed his rejection of communism. Upsetting many of his colleagues and contemporaries in France, the book brought about the final split with Sartre. The dour reception depressed Camus; he began to translate plays. Camus's first significant contribution to philosophy was his idea of the absurd. He saw it as the result of our desire for clarity and meaning within a world and condition that offers neither, which he expressed in The Myth of Sisyphus and incorporated into many of his other works, such as The Stranger and The Plague. Despite his split from his "study partner", Sartre, Camus was still categorized as an Existentialist. He specifically rejected that label in his essay "Enigma" and elsewhere. 
Which group worked against the Nazis?
The French Resistance cell Combat