Example image of eyePlorer eyePlorer map for '1820': Gregorian calendar Julian calendar Leap year starting on Saturday Leap year starting on Thursday Roman numerals Cádiz January 1 March 7 Mid-nineteenth century Spain Spanish Civil War, 1820–1823 Antarctica Fabian Gottlieb von Bellingshausen History of Antarctica January 28 Mikhail Petrovich Lazarev Russian Empire British Regency George IV of the United Kingdom January 29 Prince of Wales Edward Bransfield January 30 Capture of Valdivia Chile Thomas Cochrane, 10th Earl of Dundonald African American Freetown New York City February 14 Minh Mang Vietnam Departments of Guatemala February 20 Guatemala Santa María Chiquimula Totonicapán Department Cato Street Conspiracy February 23 March 3 March 6 May 1 Missouri Compromise Slavery United States Ferdinand VII of Spain March 9 Maine March 15 U.S. state Electricity