April 15 is the 105th day of the year (106th in leap years) in the Gregorian calendar; 260 days remain until the end of the year.
769 – The Lateran Council ends by condemning the Council of Hieria and anathematizing its iconoclastic rulings.
1071 – Bari, the last Byzantine possession in southern Italy, is surrendered to Robert Guiscard.
1191 – Henry VI, King of Germany, is crowned Holy Roman Emperor by pope Celestine III.
1277 – The Mamluk Sultanate defeats the Mongols in the battle of Elbistan 1450 – Battle of Formigny: Toward the end of the Hundred Years' War, the French attack and nearly annihilate English forces, ending English domination in Northern France.
1632 – Battle of Rain: Swedes under Gustavus Adolphus defeat the Holy Roman Empire during the Thirty Years' War.
1642 – Irish Confederate Wars: A Confederate Irish militia is routed in the Battle of Kilrush when it attempts to halt the progress of a Royalist Army.
1715 – The Pocotaligo Massacre triggers the start of the Yamasee War in colonial South Carolina.
1736 – Foundation of the short-lived Kingdom of Corsica.
1755 – Samuel Johnson's A Dictionary of the English Language is published in London.
1817 – Thomas Hopkins Gallaudet and Laurent Clerc found the American School for the Deaf (then called the Connecticut Asylum for the Education and Instruction of Deaf and Dumb Persons), the first American school for deaf students, in Hartford, Connecticut.
1861 – President Abraham Lincoln calls for 75,000 militiamen to quell the insurrection that soon became the American Civil War.
1865 – President Abraham Lincoln dies after being shot the previous evening by actor John Wilkes Booth.[13] Three hours later, Vice President Andrew Johnson is sworn in as president.
1892 – The General Electric Company is formed 1912 – The British passenger liner RMS Titanic sinks in the North Atlantic at 2:20 a.m., two hours and forty minutes after hitting an iceberg. Only 710 of 2,224 passengers and crew on board survive.
1920 – Two security guards are murdered during a robbery in South Braintree, Massachusetts. Anarchists Sacco and Vanzetti would be convicted of and executed for the crime, amid much controversy.
1922 – U.S. Senator John B. Kendrick of Wyoming introduces a resolution calling for an investigation of a secret land deal, which leads to the discovery of the Teapot Dome scandal.
1923 – Insulin becomes generally available for use by people with diabetes.
1923 – Racially motivated Nihon Shōgakkō fire lit by a serial arsonist kills 10 children in Sacramento, California.
1936 – First day of the Arab revolt in Mandatory Palestine.
1941 – In the Belfast Blitz, 200 bombers of the German Luftwaffe attack Belfast, killing some 1,000 people.
1942 – The George Cross is awarded 'to the island fortress of Malta' by King George VI.
1945 – Bergen-Belsen concentration camp is liberated.
1947 – Jackie Robinson debuts for the Brooklyn Dodgers, breaking baseball's color line.
1952 – First flight of the Boeing B-52 Stratofortress.
1955 – McDonald's restaurant dates its founding to the opening of a franchised restaurant by Ray Kroc, in Des Plaines, Illinois.
1960 – At Shaw University in Raleigh, North Carolina, Ella Baker leads a conference that results in the creation of the Student Nonviolent Coordinating Committee, one of the principal organizations of the civil rights movement in the 1960s.
1969 – The EC-121 shootdown incident: North Korea shoots down a United States Navy aircraft over the Sea of Japan, killing all 31 on board.
1970 – During the Cambodian Civil War, massacre of the Vietnamese minority results in 800 bodies flowing down the Mekong river