In this fourth volume, the series delves deeply into the insignia of the newest legion regiment, formed in 1999: the 2e Régiment Étranger de Génie (2e REG). Despite its infancy, the regiment forged a reputation through bitter combat, blood, sweat, and sacrifice in the mountains of Afghanistan and deserts of the Sahel. Through numerous campaigns and operations, this young regiment has compiled an impressive array of insignia, for which there is minimal information accessible to collectors. The author, along with members of the regiment and the collecting community, has assembled the most comprehensive database of 2e REG insignia presented in this volume, spanning from its origin in 1999 up until August 2025. Including a succinct overview of the regiment and showcasing 220 insignia, 88 patches, and 26 photographs, this work is a vital resource for collectors or anyone fascinated by the French Foreign Legion.