U-boats deposited agents spreading Anthrax and Plague, and infected with infectious stage small pox in Argentina, India, South Africa, New Zealand and Australia. Figured it would take three subs, but it was more or less gilding the lily.
Reich agents poisoning the Ganges immediately prior to the Avatarana.
Nerve gas attack on Palestine, especially Jerusalem on April 24, 1959 (1st day of passover). I came REALLY close to using this one since it so perfectly summed up the Nazi belief system.
Biological attacks against the Canadian & U.S. agricultural system. Plague, small pox, dengue fever, Yellow Fever (gotta love those 'skeeters) seeding across the U.S. Gulf Coast and Brazil.
Early versions of engineered bugs used by the Reich.
Wholesale use of human shields, especially children, by the SS during the Himmler offensive (Again this ALMOST made the cut).
Whole bunch of other really unpleasant stuff that I won't bring up since, well, it is both really nasty and/or I still might use it.