Events on April 21 42
Year 900
The Laguna Copperplate Inscription (the earliest known written document found in what is now the Philippines): the Commander-in-Chief of the Kingdom of Tondo, as represented by the Honourable Jayadewa, Lord Minister of Pailah, pardons from all debt the Honourable Namwaran and his relations.
Year 1092
The Diocese of Pisa is elevated to the rank of metropolitan archdiocese by Pope Urban II
Year 1506
The three-day Lisbon Massacre comes to an end with the slaughter of over 1,900 suspected Jews by Portuguese Catholics.
Year 1526
The last ruler of the Lodi dynasty, Ibrahim Lodi is defeated and killed by Babur in the First Battle of Panipat.
Year 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.
Year 1792
Tiradentes, a revolutionary leading a movement for Brazil's independence, is hanged, drawn and quartered.
Year 1802
Twelve thousand Wahhabis under Abdul-Aziz bin Muhammad, invaded city of Karbala, killed over three thousand inhabitants, and sacked the city.
Year 1806
Action of 21 April 1806: A French frigate escapes British forces off the coast of South Africa.
Year 1809
Two Austrian army corps are driven from Landshut by a First French Empire army led by Napoleon as two French corps to the north hold off the main Austrian army on the first day of the Battle of Eckmühl.
Year 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.
Year 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.
Year 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.
Year 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.
Year 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.
Year 1914
Ypiranga incident: A German arms shipment to Mexico is intercepted by the U.S. Navy near Veracruz.
Year 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.
Year 1926
Al-Baqi cemetery, former site of the mausoleum of four Shi'a Imams, is leveled to the ground by Wahhabis.
Year 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).
Year 1945
World War II: Soviet forces south of Berlin at Zossen attack the German High Command headquarters.
Year 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.
Year 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.
Year 1963
The first election of the Universal House of Justice is held, marking its establishment as the supreme governing institution of the Bahá'í Faith.
Year 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.
Year 1966
Rastafari movement: Haile Selassie of Ethiopia visits Jamaica, an event now celebrated as Grounation Day.
Year 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.
Year 1975
Vietnam War: President of South Vietnam Nguyễn Văn Thiệu flees Saigon, as Xuân Lộc, the last South Vietnamese outpost blocking a direct North Vietnamese assault on Saigon, falls.
Year 1982
Baseball: Rollie Fingers of the Milwaukee Brewers becomes the first pitcher to record 300 saves.
Year 1985
The compound of the militant group The Covenant, The Sword, and the Arm of the Lord surrenders to federal authorities in Arkansas after a two-day government siege.
Year 1987
The Tamil Tigers are blamed for a car bomb that detonates in the Sri Lankan capital city of Colombo, killing 106 people.
Year 1989
Tiananmen Square protests of 1989: In Beijing, around 100,000 students gather in Tiananmen Square to commemorate Chinese reform leader Hu Yaobang.
Year 1992
The first discoveries of extrasolar planets are announced by astronomers Aleksander Wolszczan and Dale Frail. They discovered two planets orbiting the pulsar PSR 1257+12.
Year 1993
The Supreme Court in La Paz, Bolivia, sentences former dictator Luis García Meza to 30 years in jail without parole for murder, theft, fraud and violating the constitution.
Year 2004
Five suicide car bombers target police stations in and around Basra, killing 74 people and wounding 160.
Year 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 Dmitry Medvedev; it was unilaterally terminated by Russia on March 31, 2014.
Year 2012
Two trains are involved in a head-on collision near Sloterdijk, Amsterdam, in the Netherlands, injuring 116 people.
Year 2014
The American city of Flint, Michigan switches its water source to the Flint River, beginning the ongoing Flint water crisis which has caused lead poisoning in up to 12,000 people, and 15 deaths from Legionnaires disease, ultimately leading to criminal indictments against 15 people, five of whom have been charged with involuntary manslaughter.
Year ?
Battle of Mutina: Mark Antony is again defeated in battle by Aulus Hirtius, who is killed. Antony fails to capture Mutina and Decimus Brutus is murdered shortly after.