Along with his brother Carl, Dilger established a laboratory in the Chevy Chase district north of Washington, DC, in which cultures of the causative agents of anthrax and glanders (Bacillus anthracis and Burkholderia mallei) were produced.

[3] In the U.S., Baltimore stevedores, who were at first recruited by German officers to plant incendiary devices among ships and wharves, were eventually given bottles of liquid culture with orders to infect horses near Van Cortland Park.

Upon his return to the U.S., Dilger found himself under suspicion of being a German agent by the Federal Bureau of Investigation and fled to Mexico, where he used the surname "Delmar."

The methods of infecting livestock became more advanced as the war progressed and went from crude needles to capillary tubes of bacterial culture hidden inside sugar cubes.

Indeed, in the treaties signed in the wake of World War I, no specific provisions were made for the prohibition of biological warfare; it is presumed officials either did not know about the German effort or did not consider it a serious threat.