In historiography there is a tendency to see the Great War as marking the end of scientific optimism and the period that followed the war as a time of discord. Connecting to current (inter)national historiographical debate on the question of whether the First World War meant a disruption from the pre-war period or not, this article strives to prove that faith in scientific progress still prevailed in the 1920s. This is shown through the use of Belgium as a case study, (...) which suggests that the generally adopted cultural pessimism in the post-war years did not apply to the public rhetoric of science in this country. Diverse actors—scientists, industrialists, politicians, the public opinion and the military staff—declared a confidence in science, enhanced by wartime results. Furthermore, belief in science in Belgium was not affected by public outcry over the use of mustard gas, unlike in the former belligerent countries where the gas became an unpleasant reminder of how science was used during the war. Even German science with its industrial applications remained the norm after 1918. In fact, the faith in science exhibited during the pre-war years continued to exist, at least until the 1920s, despite anti-German sentiments being voiced by many sections of Belgian society in the immediate aftermath of the war. (shrink)