April 5 - The New Guinea Council of Western Papua is installed.
April 8 - The British passenger ship Dara blows up and sinks off Dubai. 238 passengers and crew are killed.
April 11 - The trial of Nazi Adolf Eichmann begins in Jerusalem.
- Vostok 1: Soviet cosmonaut Yuri Gagarin becomes the first human in space, orbiting the Earth once.
- Albert Kalonji takes the title Emperor Albert I Kalonji of South Kasai.
April 13 - In Portugal, a coup attempt against António de Oliveira Salazar fails.
- The Bay of Pigs Invasion of Cuba begins; it fails by April 19.
- The 33rd Academy Awards ceremony is held.
April 18 - Portugal sends to Angola its first military reinforcement.
April 20 - Fidel Castro announces that the Bay of Pigs invasion has been defeated.
April 22 - Algiers putsch: Four French generals who oppose de Gaulle's policies in Algeria fail in a coup attempt.
April 23 - Judy Garland performs in a legendary comeback concert at Carnegie Hall in New York City.
April 24 - The Swedish ship Regalskeppet Vasa is removed from the water after being sunk 333 years earlier.
- President Kennedy delivers a revealing speech: The President and the Press: Address before the American Newspaper Publishers Association
- Sierra Leone becomes independent from the United Kingdom. (source: Wikipedia)