April 1: The Spanish Civil War comes to an end when the last of the Republican forces surrender.

April 3: Adolf Hitler orders the German military to start planning for Fall Weiss, the codename for the invasion of Poland.

April 3: Refik Saydam forms the new government in Turkey. (12 th government; Refik Saydam had served twice as a prime minister )

April 4: Faisal II becomes King of Iraq. - The Slovak-Hungarian War ends with Slovakia ceding eastern territories to Hungary.

April 7: Italy invades Albania; King Zog flees.

April 9: African-American singer Marian Anderson performs before 75,000 people at the Lincoln Memorial in Washington, D.C., after having been denied the use both of Constitution Hall by the Daughters of the American Revolution, and of a public high school by the federally controlled District of Columbia.

April 11: Hungary leaves the League of Nations.

April 13: Britain offers a "guarantee" to Romania and Greece.

April 14: John Steinbeck's novel The Grapes of Wrath is first published. - At a meeting in Paris, French Foreign Minister Georges Bonnet meets with Soviet Ambassador Jakob Suritz, and suggests that a "peace front" comprising France, the Soviet Union, Great Britain, Poland and Romania would deter Germany from war.

April 18: The Soviet Union proposes a "peace front" to resist aggression.

April 20: Billie Holiday records "Strange Fruit", the first anti-lynching song.

April 25: The Federal Security Agency (FSA) is founded in the USA, along with the Civilian Conservation Corps and Public Health Service.

April 27: Ely Racecourse in Cardiff closes.

April 28: In a speech before the Reichstag, Adolf Hitler renounces the Anglo-German Naval Agreement and the German-Polish Non-Aggression Pact.

April 30: The 1939 New York World's Fair opens. (source: Wikipedia)