After a failed siege months earlier, Crusader knights and Venetian sailors stormed Constantinople's sea walls, looting churches, palaces, and the Hagia Sophia itself over three days. The sack diverted a crusade meant for Jerusalem into the conquest of a fellow Christian empire, fracturing Byzantium into rival states and accelerating a decline that ended in the city's fall to the Ottomans in 1453.

Because no birth certificate survives, historians rely on Beethoven's baptismal record at St. Remigius Church in Bonn to place his birth around December 16 or 17, 1770; church custom of baptizing infants within a day of birth makes this record the best evidence available. He would go on to become one of history's most towering composers, reshaping music even after losing his hearing.

Under orders from General P.G.T. Beauregard, Confederate artillery bombarded the Union-held Fort Sumter for 34 hours after its commander, Major Robert Anderson, refused to surrender. No one was killed in the bombardment itself, but the attack shattered any remaining hope of peaceful reconciliation and launched four years of civil war that would kill over 600,000 Americans.

Having left Southampton the previous day, Titanic anchored briefly off Cherbourg to embark passengers ferried out by tender, since the port lacked docks large enough for her. Among those boarding were members of the wealthy Astor and Guggenheim families. The ship would sink three days later after striking an iceberg, killing over 1,500 people.

Roosevelt, serving an unprecedented fourth term and visibly exhausted from twelve years steering the nation through the Depression and World War II, collapsed while sitting for a portrait and died hours later at age 63. Vice President Harry Truman, largely uninformed about the atomic bomb project and postwar planning, was sworn in that evening to finish the war and shape the peace.

Launched from Baikonur Cosmodrome, the 27-year-old Gagarin rode Vostok 1 into orbit, radioing back the calm phrase "Poyekhali!" ("Let's go!") as the rocket left the pad. His single orbit lasted 108 minutes before he parachuted to Earth near the Volga River, instantly becoming a global celebrity and a Cold War propaganda triumph for the USSR.

Exactly twenty years after Gagarin's flight, NASA launched its first Space Shuttle, Columbia, on a two-day test mission. Commander John Young and pilot Robert Crippen proved that a winged orbiter could launch on rockets, function in orbit, and glide back to a runway landing, ushering in three decades of reusable spacecraft missions.