What happened to flags on 21 June
3 flags in the atlas carry this date. The sentence under each one is where that is written down, in its own article.
- Azerbaijan 1918
Taking inspiration from the flag of the Ottoman Empire, the ADR adopted its first state flag on 21 June 1918, which depicted a white crescent and a white eight-pointed star on a red background.
From Flag of Azerbaijan on Wikipedia, as it read on 2026-08-29
- Estonia 1940
It was taken down from the most symbolic location, the tower of Pikk Hermann in Tallinn, on 21 June 1940, when the country was still formally independent.
From Flag of Estonia on Wikipedia, as it read on 2026-08-29
- Greenland 1985
Christiansen's red-and-white flag was officially adopted on 21 June 1985.
From Flag of Greenland on Wikipedia, as it read on 2026-08-26
How a day gets onto this site
A flag is here because a sentence in its own English Wikipedia article puts it on this date, and that sentence is printed above. Nothing was worked out from a year, and nothing was written for the occasion. Every sentence names the article it came from and the version of that article it was read in, so you can go and check it.
The calendar is still short rather than full. A third of the year has no page here, because a flag only gets a day when a sentence in its article puts something on one, and plenty of articles never do. Nothing is invented to fill the gap.