"I'll Be Home for Christmas" was first copyrighted on August 24, 1943. Then it was revised and re-copyrighted on September 27, 1943, it was the 2nd version that was made famous by Crosby. The song comes from a homesick college student named Ram. Soldiers from WWII quickly picked up the song, and turned it into their sentiments, being away from home for the holidays. It quickly became a hit, and was requested frequently at U.S.O. shows.
Jingle Bells was written by James Pierpont as a Thanksgiving song in 1850 titled "One Horse Open Sleigh." It was inspired by the Massachusetts town's sleigh races. Have you heard this verse of Jingle Bells before? "A day or two ago, The story I must tell, I went out on the snow, And on my back I fell, A gent was riding by, In a one-horse open sleigh, He laughed as there I sprawling lie, But quickly drove away."
Good King Wenceslas By John Neale 1853. The song is based on a legend about a Duke named Wenceslas in Bohemia who was known for his actions of giving to the poor. He gave so much to those in need that he was know not as royalty but as a "father to the wretched."
Sources: wikipedia, "Christ in the Carols"