The first successful vaccine for smallpox was developed in 1796 by Edward Jenner. By using material from cowpox lesions, Jenner was able to provide immunity against smallpox, a devastating disease that had plagued humanity for centuries. His groundbreaking work laid the foundation for the field of immunology and established the practice of vaccination, which would lead to the eventual eradication of smallpox in the late 20th century. Jenner’s method revolutionized public health practices, promoting the idea that inoculation could prevent disease, and has had a lasting impact on global health initiatives.