Why is "We Three Kings" a Christmas hymn, and not a Lenten one? I'll admit, when I was a young'n, I thought "We Three Kings" was a silly song.  I mean, it was just about a star, right?  After all, since I only knew the chorus, and the first verse:


  We three kings of Orient are / Bearing gifts we traverse afar. 
  Field and fountain, moor and mountain, Following yonder star. 
  
  O star of wonder, star of night, 
  Star with royal beauty bright, 
  Westward leading, still proceeding, 
  Guide us to thy perfect Light. 


I figured, what a tame song.  I kinda wondered what separated this from your standard, pithy 7-11 chorus (seven words, eleven times).

Then, I started singing the whole song:


  Born a king on Bethlehem's plain, 
  Gold I bring to crown Him again, 
  King forever, ceasing never 
  Over us all to reign.
  
  Frankincense to offer have I. 
  Incense owns a Deity nigh. 
  Prayer and praising all men raising, 
  Worship Him, God on high.
  
  Myrrh is mine: it's bitter perfume 
  Breaths a life of gathering gloom. 
  Sorrowing, sighing, bleeding dying, 
  Sealed in the stone-cold tomb.
  
  Glorious now behold Him arise, 
  King and God and Sacrifice. 
  Alleluia, alleluia! 
  Sounds through the earth and skies.


Now, as I read through through this amazingly, deep, insightful sermon of a text - reading the crucifixion into the gifts of the wise men, I'm kinda blown away.  In five short verses, we have the entire life story of Jesus, prefigured in the verses.  

Given that understanding, then, why is this hymn restricted to Epiphany, and not also pulled out during the Lenten preparation for the cross?
Just noticed this during Mass today (Feast of the Epiphany). After the gospel is read, the proclamation of dates for the movable feasts can be read 

http://www.usccb.org/prayer-and-worship/liturgical-resources/christmas/announcement-of-easter-and-the-moveable-feasts.cfm

So, We Three Kings, although often thought of as a Christmas hymn is really the only popular English Epiphany hymn that I know of. And that event may have taken place 2 years after Jesus' birth for all we know. Anyway, it's a pretty good bridge for the end of the Christmas season to the beginning of Lent. 

Oh, and nobody but Lew Wallace is still thinking about the three kings when Lent comes around.