Solar Calendar -- When was the leap day inserted?

If the year started on, for example, 1 March(in some places during the 15th century), two months later than our present year, when was the leap day inserted?
Thank you.

Whenever you want. You just need one every four years (plus minor adjustments) - there's no need for it to be any particular date.

thanks.
however my question was when really it happenned? Meaning, if the year starts the first january the leap year is on the year you can divide by 4(let's say 1666).But when the year started in march was the leap year the year before(1665)?

I see. No idea - probably searchable, though.

ethan2 said:

But when the year started in march was the leap year the year before(1665)?

No. The leap day was inserted one year late for the period of the calendar use.

https://en.wikipedia.org/wiki/Gregorian_calendar#Beginning_of_the_year
https://en.wikipedia.org/wiki/Bissextus
https://en.wikipedia.org/wiki/Intercalation_(timekeeping)

Ibix said:

I see. No idea - probably searchable, though.

no problem thanks

Baluncore said:

No. The leap day was inserted one year late for the period of the calendar use.

https://en.wikipedia.org/wiki/Gregorian_calendar#Beginning_of_the_year
https://en.wikipedia.org/wiki/Bissextus
https://en.wikipedia.org/wiki/Intercalation_(timekeeping)

thank you very much
i did however found this on the web (though he is not sure) :"

Then what about leap years?​

If the year started on, for example, 1 March, two months later than our present year, when was the leap day inserted?

When it comes to determining if a year is a leap year, since AD 8 the Julian calendar has always had 48 months between two leap days. So, in a country using a year starting on 1 March, 1439 would have been a leap year, because their February 1439 would correspond to February 1440 in the January-based reckoning.

ethan2 said:

If the year started on, for example, 1 March, two months later than our present year, when was the leap day inserted?

It depends on what the Church decided it should be, with the calendar they used back then.

"Intercalation or embolism in timekeeping is the insertion of a leap day, week, or month into some calendar years to make the calendar follow the seasons or moon phases." Wikipedia.