Hello all, I'm doing some research and hope someone can verify or constructively dispute the following:
Moses was told to have the people of Israel to kill the passover lamb on the 14th and they were to eat it in "Haste" fully dressed with shoes on the feet and staff in hand. That night (15th since the sun has set) The Egyptian firstborns died, Moses and Aarron are called and told to take Israel out. This is "A Night to be Much Remembered".
The Passover is not a "Day" but an event, and the passover meal was taken by the Israelites on the evening of the 14th and 15th.
This makes sense because they were to leave the next morning, hence the need to be dressed and ready to go after eating the passover lamb whose blood was placed on the door posts to protect them from the destroyer that would pass-over them that night and kill the first-born of the unmarked door-posts.
The 14th is then refered to as the Preperation Day for the First Day of Unleaved Bread as well as Passover.