Switch from Julian to Gregoran calendar?

Pretty sure it was better science and astronomy observations 🔭 that lead to the conclusion the calendar was off, so this was a correction to make sure the solstice and equinox would occur on the proper date. And yes, also switch calendars entirely.

now you're asking the real questions 👀

The great feast of 1582.

It was legendary as it lasted for days and cost many lives. No one could remember which day of the week it was so they just rebooted everything on a Saturday