Wikipedia:Selected anniversaries/March 18
March 18: Flag Day in Aruba (1976)
- 1229 - Sixth Crusade: Holy Roman Emperor Frederick II declared himself King of Jerusalem.
- 1438 - Albert II of Habsburg became King of the Romans in the Holy Roman Empire.
- 1921 - The Polish-Bolshevik War, which determined the borders between the Republic of Poland and Soviet Russia, formally concluded with the signing of the Peace of Riga.
- 1922 - Mahatma Gandhi was sentenced to six years in prison for civil disobedience.
- 1965 - Cosmonaut Aleksei Leonov donned a spacesuit and ventured outside the Voskhod 2 spacecraft to become the first person to walk in space.