non-nuclear explosions in history. 'Mrs. Ples', an Australopithecus africanus skull, is discovered in the Sterkfontein area in Transvaal, South Africa. April 20 – King Frederik IX succeeds his father, Christian X, on the throne of Denmark. April 26 – Academy Award-winning Tom and Jerry cartoon, The Cat Concerto, is released to theatres. May May 1 – Portella della Ginestra massacre: The Salvatore Giuliano gang of Sicilian separatists opens fire on a Labour Day parade at Portella della Ginestra, Sicily, killing 11 people and wounding 27. May 2 – The movie Miracle on 34th Street, a Christmastime classic, is first shown in theaters. May 3 – The new post-war Constitution of Japan goes into effect. May 11 – The Ferrari 125 S, the first car to bear the Ferrari name, debuts. May 22 The Cold War begins: In an effort to fight the spread of Communism, President Harry S. Truman signs an Act of Congress that implements the Truman Doctrine. This Act grants $400 million in military and economic aid to Turkey and Greece. The Cold War ends in 1991. David Lean's film Great Expectations, based on the novel by Charles Dickens, opens in the United States. Critics call it the finest film ever made from a Charles Dickens novel. May 25 – Hyundai Togun, the initial name of the Hyundai Group, is founded by Chung Ju-young. May 29 An Air Iceland Douglas C-47 on a domestic flight in Iceland crashes into a mountainside killing all 25 people on board. A United States Army Air Forces Douglas C-54 Skymaster crashes on approach to Naval Air Station Atsugi, Japan, killing all 41 on board in the worst aviation accident in Japanese history up to this time. Douglas DC-4 Mainliner Lake Tahoe, operating as United Airlines Flight 521, fails to become airborne while attempting to take off from LaGuardia Airport in New York City, runs off the end of the runway, and slams into an embankment, killing 42 of the 48 people on board in the worst aviation disaster in American history until the following day. May 30 – Eastern Air Lines Flight 605: A Douglas C-54 Skymaster crashes near Bainbridge, Maryland, killing all 53 aboard (49 passengers, 4 crew), in America's worst commercial aviation disaster to that date. May 31 Ferenc Nagy, the democratically elected prime Minister of Hungary, is forced into resign and go exile under pressure from the Soviet-backed Hungarian