A disease we took a great effort in eradicating, may be used against us. The use of Smallpox as biological warfare is not unheard of. In fact, Smallpox has been used as a weapon since the 1700s, when the British fought with France for the control of Canada. And as a result, many Native Americans fell victim to the disease and perished.
At the time of the Pontiac rebellion in 1763, Sir Jeffrey Amherst, the Commander-in Chief of the British forces in North America, wrote to Colonel Henry Bouquet: 'Could it not be contrived to send smallpox among these disaffected tribes of Indians? We must use every stratagem in our power to reduce them.' The colonel replied: 'I will try to inoculate the [Native American tribe] with some blankets that may fall in their hands, and take care not to get the disease myself.' (Silent Weapon: Small Pox and Biological Warfare)
A little over 10 years later, in 1775, during the Revolutionary War, the British, once again, used this disease as a weapon, this time in an effort to prevent Americans from taking over Quebec. Apparently, one of the British commanders had civilians, who were immunized against Smallpox, infect American troops, who had no immunity. This resulted in a Smallpox epidemic, infecting about half of the 10,000 American troops.
Nearly 200 years later, during WWII, British and American scientists considered using this infectious agent as a biological weapon. However, this proved impractical, as there were vaccines readily available.
Now that Smallpox vaccinations are no longer distributed, and there is not a numerous supply of vaccinations ready at hand, the use of Smallpox as a biological warfare agent is a scary, but possible thing that can happen in our terror-filled world.