This is a list of selected May 31 anniversaries that appear in the "On this day" section of the Main Page. To suggest a new item, in most cases, you can be bold and edit this page. Please read the selected anniversaries guidelines before making your edit. However, if your addition might be controversial or on a day that is or will soon be on the Main Page, please post your suggestion on the talk page instead.
Please note that the events listed on the Main Page are chosen based more on relative article quality and to maintain a mix of topics, not based solely on how important or significant their subjects are. Only four to five events are posted at a time and thus not everything that is "most important and significant" can be listed. In addition, an event is generally not posted this year if it is also the subject of the scheduled featured article or picture of the day.
To report an error when this appears on the Main Page, see Main Page errors. Please remember that this list defers to the supporting articles, so it is best to achieve consensus and make any necessary changes there first.
May 31: Memorial Day in the United States (2010); World No Tobacco Day; Feast of the Visitation in Roman Catholicism and Anglicanism
- 1279 BC – According to estimates accepted by most Egyptologists today, Ramesses II became Pharaoh of Egypt.
- 1223 – Mongol invasions: Mongol forces defeated a combined army of Kiev, Galich, and the Cumans on the banks of the Kalchik River in present-day Ukraine.
- 1669 – Citing poor eyesight, English naval administrator and Member of Parliament Samuel Pepys (pictured) recorded his last entry in his diary, one of the most important primary sources for the English Restoration period.
- 1889 – The South Fork Dam near Johnstown, Pennsylvania, US, failed, unleashing a torrent of 18.1 million cubic meters (4.8 billion gallons) of water that killed over 2,200 people.
- 1981 – An organized mob of police and government-sponsored paramilitias began burning the public library in Jaffna, Sri Lanka, destroying over 97,000 unique books and manuscripts in one of the most violent examples of ethnic biblioclasm of the 20th century.