46 B.C.- Battle of Thapsus: Julius Caesar defeats Caecilius Metellus Scipio and Marcus Porcius Cato (Cato the Younger) near Thapsus in modern-day Tunisia
1453-Turkish forces under Sultan Mehmed II begin the siege of the Byzantine Empire's capital, Constantinople (now Istanbul), which falls on May 29
1652-Cape Colony, the first European settlement in South Africa, is established by the Dutch East India Company under Jan van Riebeeck
1917-The United States declares war on Germany and enters World War I on the side of the Allies
1931-Linus Pauling's seminal chemistry work "The Nature of the Chemical Bond" is published establishing valence bond theory
1985-Sudan suspends constitution after coup under general Swarreddahab
1994-Plane carrying Rwandan President Juvénal Habyarimana and Burundian President Cyprien Ntaryamira is shot down by surface-to-air missiles, abruptly ending peace negotiations and sparking the Rwandan Genocide. Those responsible have never been identified.