Births on April 20

Dario Knežević, Croatian footballer

Dario Knežević (born 20 April 1982) is a former Croatian footballer who played as a defender.

4 May

Falklands War
Twenty sailors are killed when the British Type 42 destroyer HMS Sheffield is hit by an Argentinian Exocet missile during the Falklands War.
25 May

Falklands War
HMS Coventry is sunk during the Falklands War.
6 Jun

Operation Peace for the Galilee
The Lebanon War begins. Forces under Israeli Defense Minister Ariel Sharon invade southern Lebanon during Operation Peace for the Galilee, eventually reaching as far north as the capital Beirut.
11 Sep

1982 Invasion of Lebanon
The international forces that were guaranteeing the safety of Palestinian refugees following Israel's 1982 Invasion of Lebanon leave Beirut. Five days later, several thousand refugees are massacred in the Sabra and Shatila refugee camps by Phalange forces.
14 Oct

War on Drugs
U.S. President Ronald Reagan proclaims a War on Drugs.