43 BC – Battle of Forum Gallorum: Mark Antony, besieging Caesar's assassin Decimus Brutus in Mutina, defeats the forces of the consul Pansa, but is then immediately defeated by the army of the other consul, Hirtius.
69 – Vitellius, commander of the Rhine armies, defeats Emperor Otho in the Battle of Bedriacum and seizes the throne.
70 – Siege of Jerusalem: Titus, son of emperor Vespasian, surrounds the Jewish capital, with four Roman legions.
193 – Septimius Severus is proclaimed Roman Emperor by the army in Illyricum (in the Balkans).
966 – After his marriage to the Christian Dobrawa of Bohemia, the pagan ruler of the Polans, Mieszko I, converts to Christianity, an event considered to be the founding of the Polish state.
1028 – Henry III, son of Conrad, is elected king of the Germans.
1205 – Battle of Adrianople between Bulgarians and Crusaders.
1294 – Temür, grandson of Kublai, is elected Khagan of the Mongols and Emperor of the Yuan Dynasty with the reigning titles Oljeitu and Chengzong.
1341 – Sack of Saluzzo (Italy) by Italian-Angevine troops under Manfred V of Saluzzo.
1434 – The foundation stone of Cathedral St. Peter and St. Paul in Nantes, France is laid.
1471 – In England, the Yorkists under Edward IV defeat the Lancastrians under the Earl of Warwick at the Battle of Barnet; the Earl is killed and Edward IV resumes the throne.
1639 – Imperial forces are defeated by the Swedes at the Battle of Chemnitz. The Swedish victory prolongs the Thirty Years' War and allows them to advance into Bohemia.
1699 – Khalsa: The Sikh religion was formalised as the Khalsa - the brotherhood of Warrior-Saints - by Guru Gobind Singh in Northern India, in accordance with the Nanakshahi calendar.
1715 – The Yamasee War begins in South Carolina.
1775 – The first abolition society in North America is established. The Society for the Relief of Free Negroes Unlawfully Held in Bondage is organized in Philadelphia, Pennsylvania by Benjamin Franklin and Benjamin Rush.
1816 – Bussa, a slave in British-ruled Barbados, leads a slave rebellion and is killed. For this, he is remembered as the first national hero of Barbados.
1828 – Noah Webster copyrights the first edition of his dictionary.
1846 – The Donner Party of pioneers departs Springfield, Illinois, for California, on what will become a year-long journey of hardship, cannibalism, and survival.
1849 – Hungary declares itself independent of Austria with Lajos Kossuth as its leader.
1860 – The first Pony Express rider reaches San Francisco. The pony riders carried additionally, along with the mail, a small personal bible.
1865 – U.S. President Abraham Lincoln is shot in Ford's Theatre by John Wilkes Booth (died April 15th).
1865 – U.S. Secretary of State William H. Seward and his family are attacked in his home by Lewis Powell.
1881 – The Four Dead in Five Seconds Gunfight is fought in El Paso, Texas.
1890 – The Pan-American Union is founded by the First International Conference of American States in Washington, D.C.
1894 – The first ever commercial motion picture house opened in New York City using ten Kinetoscopes, a device for peep-show viewing of films.
1906 – The Azusa Street Revival opens and will launch Pentecostalism as a worldwide movement.
1909 – A massacre is organized by Ottoman Empire against Armenian population of Cilicia.
1912 – The British passenger liner RMS Titanic hits an iceberg in the North Atlantic at 23:40 (sinks morning of April 15th).
1927 – The first Volvo car premieres in Gothenburg, Sweden.
1928 – The Bremen, a German Junkers W33 type aircraft, reaches Greenly Island, Canada - the first successful transatlantic aeroplane flight from east to west.
1931 – The Spanish Cortes deposes King Alfonso XIII and proclaims the Second Spanish Republic.
1931 – First edition of the Highway Code published in Great Britain.
1935 – "Black Sunday Storm", the worst dust storm of the U.S. Dust Bowl.
1939 – The Grapes of Wrath, by American author John Steinbeck is first published by the Viking Press.
1940 – World War II: Royal Marines land in Namsos, Norway in preparation for a larger force to arrive two days later.
1941 – World War II: German general Erwin Rommel attacks Tobruk.
1942 – Malta receives the George Cross for its gallantry. The George Cross was given by King George VI himself and is now an emblem on the Maltese national flag.
1944 – Bombay Explosion: A massive explosion in Bombay harbor kills 300 and causes economic damage valued then at 20 million pounds.
1945 – Osijek, Croatia, is liberated from fascist occupation.
1956 – In Chicago, videotape is first demonstrated.
1958 – The Soviet satellite Sputnik 2 falls from orbit after a mission duration of 162 days.
1967 – Gnassingbé Eyadéma overthrows President of Togo Nicolas Grunitzky and installs himself as the new president, a title he would hold for the next 38 years.
1969 – At the U.S. Academy Awards there is a tie for the Academy Award for Best Actress between Katharine Hepburn and Barbra Streisand.
1978 – 1978 Tbilisi Demonstrations: Thousands of Georgians demonstrate against Soviet attempts to change the constitutional status of the Georgian language.
1981 – STS-1 – The first operational space shuttle, Columbia (OV-102) completes its first test flight.
1986 – In retaliation for the April 5 bombing in West Berlin that killed two U.S. servicemen, U.S. president Ronald Reagan orders major bombing raids against Libya, killing 60 people.
1986 – The heaviest hailstones ever recorded (1 kilogram (2.2 lb)) fall on the Gopalganj district of Bangladesh, killing 92.
1988 – The USS Samuel B. Roberts strikes a mine in the Persian Gulf during Operation Earnest Will.
1988 – In a United Nations ceremony in Geneva, Switzerland, the Soviet Union signs an agreement pledging to withdraw its troops from Afghanistan.
1991 – The Republic of Georgia introduces the post of President after its declaration of independence from the Soviet Union.
1994 – In a U.S. friendly fire incident during Operation Provide Comfort in northern Iraq, two United States Air Force aircraft mistakenly shoot-down two United States Army helicopters, killing 26 people.
1999 – NATO mistakenly bombs a convoy of ethnic Albanian refugees – Yugoslav officials say 75 people were killed.
1999 – A severe hailstorm strikes Sydney, Australia causing A$2.3 billion in insured damages, the most costly natural disaster in Australian history.
2002 – Venezuelan President Hugo Chávez returns to office two days after being ousted and arrested by the country's military.
2003 – The Human Genome Project is completed with 99% of the human genome sequenced to an accuracy of 99.99%.
2003 – U.S. troops in Baghdad capture Abu Abbas, leader of the Palestinian group that killed an American on the hijacked cruise liner the MS Achille Lauro in 1985.
2005 – The Oregon Supreme Court nullifies marriage licenses issued to gay couples a year earlier by Multnomah County.
2007 – At least 200,000 demonstrators in Ankara, Turkey, protest against the possible candidacy of incumbent Prime Minister Recep Tayyip Erdoğan.
2010 – Nearly 2,700 are killed in a magnitude 6.9 earthquake in Yushu, Qinghai, China.
2014 – Twin bomb blasts in Abuja, Nigeria, kill at least 75 people and injures 141 others.