The Last Supper, depending if you read the Synoptics or John, was either a Passover Seder (Synoptics), or the Prepartory meal the day before the Passover (in John). This is very obvious in the Gospels themselves. (Mt 26:17-19, Mk. 14:12-16, Lk.22:7-13, Jn. 13:1)
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