- 1146 Bernard of Clairvaux preaches his famous sermon in a field at Vézelay, urging the necessity of a Second Crusade. Louis VII is present, and joins the Crusade.
- 1492 Queen Isabella and King Ferdinand of Aragon issue the Alhambra Decree which expels Jews from their Kingdoms of Castile and Aragon
- 1657 English Parliament makes the Humble Petition to Lord Protector Oliver Cromwell offering him the crown: he declines
- 1920 British parliament accepts Irish Home Rule law
- 1965 US orders first combat troops to Vietnam
Eiffel Tower officially opens in Paris. Built for the Exposition Universelle, at 300m high it retains the record for the tallest man made structure for 41 years.
On March 31, 1889
Thomas Mundy Peterson of Perth Amboy, New Jersey is the first African American to vote in the US (in a local election on town's charter)
On March 31, 1870