April 21 events in history

900 The Laguna Copperplate Inscription, the earliest known written document found in the Philippines: the Honourable Namwaran and his children, Lady Angkatan and Bukah, are granted pardon from all their debts by the Commander in chief of Tundun, as represented by the Honourable Jayadewa, Lord Minister of Pailah. Luzon, Philippines
1092 The Diocese of Pisa is elevated to the rank of metropolitan archdiocese by Pope Urban II
1506 The three-day Lisbon Massacre comes to an end with the slaughter of over 1,900 suspected Jews by Portuguese Catholics
1509 Henry VIII ascends the throne of England on the death of his father, Henry VII
1526 The last ruler of the Lodi Dynasty, Ibrahim Lodi is defeated and killed by Babur in the First Battle of Panipat
1615 The Wignacourt Aqueduct is inaugurated in Malta
1782 The city of Rattanakosin, now known internationally as Bangkok, is founded on the eastern bank of the Chao Phraya River by King Buddha Yodfa Chulaloke
1792 Tiradentes, a revolutionary leading a movement for Brazil's independence, is hanged, drawn and quartered
1806 Action of 21 April 1806: A French frigate escapes British forces off the coast of South Africa
1809 Two Austrian army corps are driven from Landshut by a First French Empire army led by Napoleon I of France as two French corps to the north hold off the main Austrian army on the first day of the Battle of Eckmühl
1821 Benderli Ali Pasha arrives in Constantinople as the new Grand Vizier of the Ottoman Empire; he remains in power for only nine days before being sent into exile
1836 Texas Revolution: The Battle of San Jacinto: Republic of Texas forces under Sam Houston defeat troops under Mexican General Antonio López de Santa Anna
1856 Australian labour movement: Stonemasons and building workers on building sites around Melbourne march from the University of Melbourne to Parliament House to achieve an Eight-hour day
1863 Bahá'u'lláh, the founder of the Bahá'í Faith, declares his mission as "He whom God shall make manifest"
1894 Norway formally adopts the Krag-Jørgensen bolt-action rifle as the main arm of its armed forces, a weapon that would remain in service for almost 50 years
1898 Spanish–American War: The United States Navy begins a blockade of Cuban ports. When the U.S. Congress issued a declaration of war on April 25, it declared that a state of war had existed from this date
1914 Ypiranga incident: A German arms shipment to Mexico is intercepted by the U.S. Navy near Veracruz, Veracruz
1918 World War I: German fighter ace Manfred von Richthofen, better known as "The Red Baron", is shot down and killed over Vaux-sur-Somme in France
1925 The Manifesto of the Fascist Intellectuals is published in Il Mondo, establishing the political and ideological foundations of Italian Fascism
1934 The "Surgeon's Photograph", the most famous photo allegedly showing the Loch Ness Monster, is published in the Daily Mail (in 1999, it is revealed to be a hoax)
1941 Emmanouil Tsouderos becomes the 132nd Prime Minister of Greece
1945 World War II: Soviet forces south of Berlin at Zossen attack the German High Command headquarters
1952 Secretary's Day (now Administrative Professionals' Day) is first celebrated
1960 Brasília, Brazil's capital, is officially inaugurated. At 09:30, the Three Powers of the Republic are simultaneously transferred from the old capital, Rio de Janeiro
1962 The Seattle World's Fair (Century 21 Exposition) opens. It is the first World's Fair in the United States since World War II
1963 The Universal House of Justice of the Bahá'í Faith is elected for the first time
1964 A Transit-5bn satellite fails to reach orbit after launch; as it re-enters the atmosphere, 2.1 pounds (0.95 kg) of radioactive plutonium in its SNAP RTG power source is widely dispersed
1965 The 1964–1965 New York World's Fair opens for its second and final season
1966 Rastafari movement: Haile Selassie of Ethiopia visits Jamaica, an event now celebrated as Grounation Day
1967 Greek military junta of 1967–74: A few days before the general election in Greece, Colonel George Papadopoulos leads a coup d'état, establishing a military regime that lasts for seven years
1970 The Hutt River Province Principality secedes from Australia
1975 Vietnam War: President of South Vietnam Nguyen Van Thieu flees Saigon, as Xuan Loc, the last South Vietnamese outpost blocking a direct North Vietnamese assault on Saigon, falls
1982 Baseball: Rollie Fingers of the Milwaukee Brewers becomes the first pitcher to record 300 saves
1987 The Tamil Tigers are blamed for a car bomb that detonates in the Sri Lankan capital city of Colombo, killing 106 people
1989 Tiananmen Square Protests of 1989: In Beijing, around 100,000 students gather in Tiananmen Square to commemorate Chinese reform leader Hu Yaobang
1992 The first discoveries of extrasolar planets are announced by astronomers Alexander Wolszczan and Dale Frail. They discovered two planets orbiting the pulsar PSR 1257+12
1993 The Supreme Court in La Paz, Bolivia, sentences former dictator Luis Garcia Meza to 30 years in jail without parole for murder, theft, fraud and violating the constitution
2004 Five suicide car bombers target police stations in and around Basra, killing 74 people and wounding 160
2010 The controversial Kharkiv Pact (Russian Ukrainian Naval Base for Gas Treaty) is signed in Kharkiv, Ukraine, by Ukrainian President Viktor Yanukovych and Russian President Dimitry Medvedev; it will be unilaterally terminated by Russia on March 31, 2014
2012 Two trains are involved in a head-on collision near Sloterdijk, Amsterdam, in the Netherlands, injuring 116 people