The German army's 1943 flooding of the Pontine Marshes south of Rome, which later caused a sharp rise in malaria cases among Italian civilians, has recently been described by historian Frank Snowden as a unique instance of biological warfare and bioterrorism in the European theater of war and, consequently, as a violation of the 1925 Geneva Protocol prohibiting chemical and biological warfare. We argue that archival documents fail to support this allegation, on several counts. As a matter of historical record, Hitler prohibited German biological weapons (BW) development and consistently adhered to the Geneva Protocol. Rather than biological warfare against civilians, the Wehrmacht used flooding, land mines, and the destruction of vital infrastructure to obstruct the Allied advance. To protect its own troops in the area, the German army sought to contain the increased mosquito breeding likely to be caused by the flooding. Italians returning to the Pontine Marshes after the German retreat in 1944 suffered malaria as a result of environmental destruction, which was banned by the 1899 and 1907 Hague Conventions and by subsequent treaties. In contrast, a state's violation of the Geneva Protocol, whether past or present, involves the use of germ weapons and, by inference, a state-level capability. Any allegation of such a serious violation demands credible evidence that meets high scientific and legal standards of proof.