The well known Christmas carol, Adeste Fideles has a very interesting history. It was written in the mid eighteenth century by John Francis Wade, a Catholic Englishman, who fled the religious persecution back at home. He eventually settled in Douay, France, which was the site of a large Catholic college, and the home in exile for many English, Scottish and Irish Catholics. John Wade made his living by copying and selling plain chant and other music, and encouraged the revival of plain chant in Divine worship. The earliest known manuscript of Adeste Fideles was written in 1743 or 1744, and in known as the Jacobite Manuscript, because it contains a prayer for King James III, father of Bonnie Prince Charlie. The song went through several revisions before it was published in France in the Evening Offices of the Church. It was published in England more that 20 years later, in a work entitled, Essay or Instruction for Learning the Church Plain Chant. It is rather remarkable that a piece of music, written in Latin, by a virtually unknown author who was a member of a persecuted Church and a supporter of an exiled King, should have gone on to become one of the most well-known Christmas carols in the world.
For an in depth history of Adeste Fideles, go to this website. It is very good. And here is a rather fine arrangement clip of Adeste Fideles for classical guitar: