What significant historical events occurred at such a time and place that the local calendar, if any, would have indicated 1700/02/29? I do not get what you mean. Osmo

Finnish calendars definitely have leap day ( karkausp=E4iv=E4 ) = marked on Feb 24th. But the origin of this (counterintuitive) practice is unknown to me. That comes from Roman, pre-Julian days. Back then February was the last month of the year so it was natural that it changed in length. The last week of it was considered some kind of extra time that was used for all kind of corrections. Now I do not know if Romans had 7 or 8 days in a week (I have heard both stated) but 24th would have been the beginning of the last week with 7 days week and 30 days in February (before Caesar and Augustus each stole one day) Osmo

Saints days (as they're known in the rest of world, if known at all...) were assigned while the Julian calendar was still in use.  So while the fact that St. Matthew's day jumps about is an interesting historical curiosity, it doesn't reflect the current, Gregorian calendar. I wonder what is the Saint Osmo who has his name day on May 11th. The make days may have originated as the days of Saints but they are not those anymore. And I wonder who Saint Jani is?  Well, turns out that if you look up the history of the name, it's derived from Johannes , which in turn comes from the person now known as St. John. Now, quite a few purely Finnish names (while probably include Osmo) are included in the name day listings, but they were presumably scattered about at random by early church fathers

At least here leap day is the 24th February. Huh?  I don't know why on earth you insist on this. Because it is true. Check any calendar. (of a leap year)                           ^^^ Come come - **any** calendar?  That's too strong; my HMSO 1996 one does not give such detail.  Precision! We're obviously dealing with an _interesting_ cultural difference.  Let's not argue about it, let's find out more. I remember how shocked I was the first time I saw some Dutch calendars (circa 1971, in Curacao) in which the days of each week formed a _vertical_ column (you know, row-major instead of row-minor or some such thing... ninety degree rotation).  It wasn't that the Dutch always did it that way, but that apparently Dutch graphic designers decided that it was perfectly all right to change aspects of the calendar layout that us dull, conservative Americans (U.S.) thought were sacred. Osmo: in the United States, the vast majority of ordinary calendars do NOT give saint's days, name days, or any other liturgical information. Typically they identify: national holidays; widely accepted state holidays; various days loosely identified with sending greeting cards (Valentine's Day, Mother's Day)

What significant historical events occurred at such a time and place that the local calendar, if any, would have indicated 1700/02/29? I do not get what you mean. Sorry, I can see no better way of putting the question - anyone else like to try?