Q: WHAT YEAR WAS THE GREAT PASSOVER?
A: IT DEPENDS WHAT CALENDAR YOU ARE USING!
On the Gregorian calendar (the one you might have on your wall) the year was 558 BC.
On the Hebrew calendar, sometimes called the biblical calendar, the year was 3489 AM.
Exodus 12:11 And thus you shall eat it: with a belt on your waist, your sandals on your feet, and your staff in your hand. So you shall eat it in haste. It is the Lord's Passover.