The largest tornado outbreak ever recorded hits the U.S.. 348 people in six states were killed during the outbreak, which encompassed a total of 358 confirmed tornadoes.

The German news magazine, Stern, announces discovery of Hitler's diaries. The documents were later exposed as forgeries, triggering one of the most spectacular media scandals in history. Experts believe that Hitler never kept a diary.

In Portugal, the fascist Estado Novo regime is overthrown in a bloodless coup. The leftist Carnation Revolution was led by military officers and supported by widespread civil resistance.

The double helix structure of DNA described for the first time. Francis Crick and James D. Watson published their groundbreaking findings about the molecule containing genetic information was in Nature that day.

Construction of the Suez Canal begins. The waterway connecting the Mediterranean Sea and the Red Sea became the shortest sea link between Europe and Asia.