This day in history

American Dr. Jonas Salk reports that he has successfully tested a vaccine against poliomyelitis, the virus that causes the crippling disease of polio.

Polio, a disease that mainly affects children, attacks the nervous system and can cause paralysis. Since the virus is easily transmitted, epidemics were commonplace in the first decades of the 20th century. Salk's discovery came in the midst of major polio epidemics in Europe, Asia and the United States. Two years later, a massive child inoculation program was underway. In 1957, the development of an oral vaccine by Polish-American researcher Albert Sabin greatly facilitated distribution of the polio vaccine.

Bangladesh declares independence form Pakistan.

Richard I, King of England, commonly referred to as Richard the Lionheart, is fatally wounded by a crossbow bolt during a siege in France.