If you were to ask any well-informed American the date of the first biological weapon on United States' soil, he or she would be quite likely to cite the anthrax terrorist attack in Washington, D.C., New York City and Florida in the fall of 2001. This use of a weapons grade bio-organism killed five people and infected 17 others. It was, however, not the first time biological weapons were used against America and in fact, the initial use was nearly ninety years prior.
The book, The Fourth Horseman, by Robert L. Koenig, pieces together the story of Anton Casimir Dilger, an American doctor of German ancestry recruited by German intelligence as a saboteur during the First World War. His means of sabotage was through the mass-production of a a highly contagious bacteria which caused an incurable disease called glanders. This germ warfare did not target humans however, but a key component in the of any army before the age of the automobile, the horse and the mule. Dilger sent agents out with vials of the deadly bacteria to loading sites at port cities with instructions to infect as many animals as possible.
Most interesting is Dilger's transformation from a dedicated American doctor, with a love and respect for horses since his youth, to a spy and saboteur responsible for the death of thousands of animals. Step by step, Dilger as an idealist and lover of the fatherland was to become merely a desperate amoral criminal on the run. When his first assignment proved less than successful, Dilger was given sent to persuade Mexico to attack the United States, thereby thwarting- or at least, delaying American entry into the European campaign. Dilger's corruption is underlined when in Mexico City he meets, his chief rival in the field, the dangerous but extremely intelligent, Kurt Jahnke. Jahnke had been recruited to perform cruder and more spectacular operations such as munition explosions, in contrast to the what Dilger thought to be his more "sophisticated acts" of sabotage.
Against the ethical question of using biological weapons against innocent animals, one could, of course, argue that these animals were unquestionably being sent to their deaths in any case. In terms of the animal's welfare, it perhaps made little real difference whether they were to die of glanders or on the battlefield. It was the carnage of horses in the war- estimated at three-quarters of a million horses and mules were killed- that led to increased efforts at animal protection.
Ironically, before the end of the war, humankind itself was faced with a threat by contagion. From March 1918 to June 1920, the Spanish flu would spread to all corners of the world and, overshadowing the casualties of the Great War, cause the deaths of 50 to 100 million people.