Wikipedia:Selected anniversaries/March 18
March 18: Flag Day in Aruba (1976).
- 1229 – Sixth Crusade: Holy Roman Emperor Frederick II crowned himself King of Jerusalem, although this was technically improper since his wife Queen Yolande of Jerusalem had died, leaving their infant son Conrad as the rightful heir.
- 1871 – French President Adolphe Thiers ordered the evacuation of Paris after an uprising broke out as the result of France's defeat in the Franco–Prussian War, leading to the establishment of the Paris Commune government.
- 1892 – Canadian Governor General Frederick Stanley of Preston pledged to donate what would become the Stanley Cup (1893 version pictured), today the oldest professional sports trophy in North America, as an award for Canada's top-ranking amateur ice hockey club.
- 1921 – The Polish–Soviet War, which determined the borders between the Republic of Poland and Soviet Russia, formally concluded with the signing of the Peace of Riga.
- 1965 – Cosmonaut Alexey Leonov donned a space suit and ventured outside the Voskhod 2 spacecraft, becoming the first person to walk in space.