What happened to flags on 18 August
One flag in the atlas carries this date. The sentence under it is where that is written down, in its own article.
- Sweden 1761
A royal warrant of 18 August 1761, stipulated that an all blue triple-tailed flag to be used by the archipelago fleet, a branch of the army tasked with defending the archipelago along the Swedish coastlines.
From Flag of Sweden on Wikipedia, as it read on 2026-08-29
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.