This article explores attitudes toward boyhood shaped by the traumatic experiences of the First World War. It focuses particularly on the work of the little-known French author, Paul Cazin, and his attempts to commemorate the entirety of “the lost generation” by transcending divisions of religion and secularism that characterized boyhood activities in France before the war. The figure of the “Manneken-Pis” enables him to do this and is particularly suited to the expression of conflicting attitudes toward militarism in boyhood. Cazin’s intellectual program leads to a reading of the famous Manneken-Pis fountain depicting a urinating boy as a religious artifact. A variety of interwar responses to the statue demonstrate the strength of emotion provoked by the figure of the young boy. The fact that these responses have been enshrined in modern cultural and artistic practices suggests the extent to which the experience of the First World War still conditions attitudes toward boyhood.