Wilson becomes leader of the opposition Labour Party in the United Kingdom; in October 1964 he becomes prime minister. February 21 – The 5.6 Marj earthquake affects northern Libya with a maximum Mercalli intensity of VIII (Severe), causing 290–375 deaths and 375–500 injuries. February 27 – Juan Bosch takes office as the 41st president of the Dominican Republic. March March 4 – In Paris, six people are sentenced to death for conspiring to assassinate President Charles de Gaulle. De Gaulle pardons five, but the other conspirator, Jean Bastien-Thiry, is executed by firing squad several days later. March 17 – Mount Agung erupts on Bali, killing approximately 1,500. March 23 – "Dansevise" by Grethe & Jørgen Ingmann (music by Otto Francker, text by Sejr Volmer-Sørensen) wins the Eurovision Song Contest 1963 for Denmark. March 30 – Indigenous Australians are legally allowed to drink alcohol in New South Wales. April April 7 – Yugoslavia is proclaimed to be a socialist republic, and Josip Broz Tito is named President for Life. April 8 – The 35th Academy Awards ceremony is held. Lawrence of Arabia wins Best Picture. April 10 – The U.S. nuclear submarine Thresher sinks east of Cape Cod; all 129 aboard (112 crewmen plus yard personnel) die. April 11 – Pope John XXIII issues his final encyclical, Pacem in terris, entitled On Establishing Universal Peace in Truth, Justice, Charity and Liberty, the first papal encyclical addressed to "all men of good will", rather than to Roman Catholics only. April 12 – The Soviet nuclear powered submarine K-33 collides with the Finnish merchant vessel M/S Finnclipper in the Danish Straits. Although severely damaged, both vessels make it to port. April 14 – The Institute of Mental Health (Belgrade) is established. April 16 – Martin Luther King, Jr. issues his "Letter from Birmingham Jail". April 20 – In Quebec, Canada, members of the terrorist group Front de libération du Québec bomb a Canadian Army recruitment center, killing night watchman Wilfred V. O'Neill. April 21–23 – The first election of the Supreme Institution of the Baháʼí Faith (known as the Universal House of Justice, whose seat is at the Baháʼí World Centre on Mount Carmel in Haifa, Israel) is held. April 22 – Lester Bowles Pearson becomes the 14th Prime Minister of Canada. April 28 – 1963 general election is held in Italy. April 29 – Buddy Rogers becomes the first WWWF Champion. May