What kind of mathematical research activities took place in prisoner of war camps in Germany during the Second World War? And can one inspect such activities in order to re-examine, on the one hand, Herbert Mehrtens’ analysis of the modernism/counter-modernism divide of early twentieth-century mathematics, and on the other, his research on the instrumentalization of mathematics during the war? Closely examining the work carried out in the field of algebraic geometry by the French mathematician Bernard d’Orgeval, who was held in three of such camps between 1940 and 1945, the paper aims not only to unfold this unique episode in the history of mathematics, presenting it as an ephemeral configuration, but also to show the limitations of Mehrtens’ approach and the narrative of modern and counter-modern mathematics.