Anthrax vaccines known to result in far less scarring, and greatly reduced mortality, in comparison with the naturally acquired disease. The English physician Edward Jenner (1749–1823) had also discovered (1796) the process of vaccination by using cowpox to give cross-immunity to smallpox and by Pasteur's time this had generally replaced the use of actual smallpox material in inoculation. The difference between smallpox vaccination and anthrax or chicken cholera vaccination was that the weakened form of the latter two disease organisms had been "generated artificially", so a naturally weak form of the disease organism did not need to be found. This discovery revolutionized
1837 Great Plains smallpox epidemic experienced a major smallpox epidemic in 1780-81 which severely reduced their numbers down to less than a few thousand. Many other bands along the Missouri river suffered smallpox epidemics during 1801-02 and 1831. Sporadic efforts were made to promote vaccination among the Indigenous peoples since the turn of the nineteenth century. Later, the Indian Removal Act the U.S. Congress took its first step in 1832 to generate public support for vaccination of the Native Americans. But shortly after passage of this congressional act to extend vaccinations to Indians, Secretary Cass stated that no effort would be made "under any circumstances"