In April 1956, which ruler of Monaco married American film star Grace Kelly?

In 1828, Noah Webster published what kind of landmark reference book for American English? The English army's defeat at Formigny on April 15, 1450, came near the end of which long war? April 1644, when rebels captured Beijing, is regarded as the last month of which Chinese dynasty's rule? On April 18, 1980, which country became the independent nation of Zimbabwe? April 21 is a Rastafarian holiday marking Ethiopian emperor Haile Selassie's 1966 visit to which island? April 22, Earth Day, is also the birthday of which leader of the 1917 Russian Revolution? April 29, the birthday of Emperor Hirohito, is a national holiday in which Asian country? Until 2013, which country celebrated Queen's Day on April 30, the birthday of Queen Juliana?