May 5:
A.D. 553: The Second General Council of Constantinople (fifth ecumenical council of the RCC) opens.
A.D. 1260: Kublai Khan becomes the ruler of the Mongol Empire.
A.D. 1762: Russia and Prussia sign a peace treaty in St. Petersburg, ending the Seven Years' War.
A.D. 1809: Mary Kies becomes the first woman to be issued a U.S. patent (for weaving straw).