In North America, White Settlers attempted to kill First Nations people with blankets given as gifts that were infected with smallpox
edit:
"During a parley in midst of the siege on 24 June 1763, Captain Simeon Ecuyer gave representatives of the besieging Delawares two blankets and a handkerchief enclosed in small metal boxes that had been exposed to smallpox, in an attempt to spread the disease to the Natives in order to end the siege"