The peace candle is the fourth candle lit on the Advent wreath.
But that baby, the incarnate Christ, did not come to bring peace. He tells us straight in Matthew 10:34, "Do not suppose that I have come to bring peace to the earth. I did not come to bring peace, but a sword."
We hope for peace. We pray for peace. But there will be no true, complete, lasting peace until we are spending eternity in heaven with our God. Jesus wanted us to realize that in His definitive statement in Matthew.
There are occasional glimpses of peace in our lives, fleeting and few, but I think God gives us those small tastes of peace so that we do not lose hope and so that we remember that someday there will be peace on earth.
Even now, come Lord Jesus.