May 15

• May 15, 392
  Valentinian II, emperor of Rome, is found hanged in his residence in Vienne at age 21, in south-eastern France
• May 15, 756
  The Umayyad Abd al-Rahman I establishes the government in the regions of Iberia and proclaims himself the emir of Cordoba representing a branch from the rest of the Islamic Empire
• May 15, 1213
  Stephen Langton is chosen Archbishop of Canterbury after some disputes between King John of England and Pope Innocent III
• May 15, 1525
  A German army under Landgrave Philip I of Hesse surround and slaughter 8,000 peasants at the battle of Frankenhausen ending a peasant revolt led by German theologian Thomas Müntzer
• May 15, 1602
  Bartholomew Gosnold, English navigator, discovers Cape Cod in modern-day Northeastern United States
• May 15, 1620
  The Plaza Mayor, a central plaza in the city of Madrid, Spain is opened
• May 15, 1648
  Spain and Netherlands ratify Peace of Münster, ending Eighty Years' War and recognizing the independence of the Netherlands
• May 15, 1665
  Pope Alexander VII convicts Jansenism, a Christian theological movement that emphasized original sin, human depravity, the necessity of divine grace, and predestination
• May 15, 1668
  A private bank is taken over by the Swedish State Government, becoming the Riksbank, the first national bank in the world
• May 15, 1679
  The Earl of Shaftesbury introduces his Exclusion Bill into Parliament proposing that James, the Catholic brother of King Charles II, be permanently barred from the line of succession to the English throne
• May 15, 1681
  Canal du Midi, a long canal connecting joining the Atlantic to the Mediterranean, is completed by French engineer Pierre-Paul Riquet
• May 15, 1718
  James Puckle, a London lawyer, patents world's first machine gun that utilize a revolving block for firing square bullets
• May 15, 1768
  France purchases Corsica from Genoa by the Treaty of Versailles
• May 15, 1796
  Napoleon enter the Lombardian capital of Milan in triumph
• May 15, 1811
  Paraguay gains independence from Spain
• May 15, 1836
  Francis Baily, an English astronomer, observes "Baily's Beads", a diamond ring effect during annular solar eclipse
• May 15, 1855
  Paris holds the Exposition Universelle, the second world exposition
• May 15, 1878
  The Tokyo Stock Exchange, Japan's first public trading institution and the second largest stock exchange in the world now, is formed under the direction of then-Finance Minister Okuma Shigenobu and capitalist advocate Shibusawa Eiichi
• May 15, 1882
  Emperor Alexander III enacts May Laws, which ban Jews to settle anew outside of towns and boroughs
• May 15, 1902
  Portugal declares bankrupt causing revolt in Angola, social turmoil and economic disturbances
• May 15, 1905
  Las Vegas is founded at auctioned land adjacent to the Union Pacific Railroad tracks
• May 15, 1905
  Las Vegas is founded at auctioned land, adjacent to the Union Pacific Railroad tracks
• May 15, 1905
  Las Vegas is founded at auctioned land adjacent to the Union Pacific Railroad tracks
• May 15, 1918
  Finnish Civil War between the forces of the Social Democratic Party commonly called the "Reds", and the forces of the non-socialist, conservative-led Senate, commonly called the "Whites", ends with victory of the latter
• May 15, 1932
  Inukai Tsuyoshi, premier of Japan, is murdered by reactionary elements of the Imperial Japanese Navy
• May 15, 1934
  Kārlis Ulmanis, closes all newspapers owned by political parties and suspends civil liberties, making himself fascist dictator of Latvia
• May 15, 1940
  McDonald's opens its first restaurant, in San Bernardino, California
• May 15, 1948
  Forces from Egypt, Jordan, Syria, Lebanon, and Iraq invade and attack Israel, territory in the former British Mandate, beginning First Arab-Israeli War
• May 15, 1953
  "The Destroyed City", a memorial to the destruction of the center of the Dutch city of Rotterdam in 1940, made by a Belarusian-born artist Ossip Zadkine, is unveiled
• May 15, 1955
  Britain, France, United States and USSR sign the Austrian State Treaty restore Austria's independence
• May 15, 1963
  The final Mercury mission is launched, with astronaut Gordon Cooper - who becomes the first American to spend more than a day in space
• May 15, 1988
  Soviets begin withdrawal from Afghanistan