French infantry pushing through enemy barbed wire, 1915. While originally invented to restrain cattle in Ohio, barbed wire played a pivotal role in shaping the new ways of fighting that emerged during the First World War. Preventing any kind of unified infantry charge, wire was used as a defense of the now universal trench static system. It was not until the invention of the tank that barbed wire defenses could be overcome in an effective way.

Source: Bibliothèque nationale de France (Agence Meurisse, 58736)