–As song, the form was four stanzas with fully repeating refrains, making use of much more repetition than the modern literary rondeau or its variants.  The earliest sung rondeaux developed in the thirteenth century and became well known through the compositions of Adam de la Halle, the "hunchback poet," who served as court poet and musician to the Count d'Artois.   

–The rondeau, adopted by church musicians as an emotionally rich container, continued into the fourteenth and fifteenth centuries. Not only for spiritual worship, the rondeau was also used for devotion to secular subjects such as springtime, courtly love, and romance.  Oddly, the form also clearly offered a vehicle for the celebration of melancholy.  Many rondeaux seem to be about pain and loss; yet they turn by the last stanza to a light, almost jovial statement of c'est la vie!  (Only the English, who adopted the rondeau at the end of the eighteenth century, truly attempt serious verse with this form--according to The Princeton Handbook). 
[Note: This practice compares to the American blues form.--AR]

–An example of the light, French flavor is the work of the fifteenth century French poet Vaillant, who follows the strict musical guidelines of the form with his fully repeating refrain:

                                    Listen, everyone!  I have lost my girl
  For he who finds her, on my soul
  Even though she is fair and kindly
  I give her up heartily
  Without raising a stink at all

  This girl knows her graces well
  God knows, she loves and is loyal
  For heaven's sake, let him keep her secretly
  Listen everyone!  I have lost my girl

  Look after her well, this pearl
  Let no one hurt or wound her
  For by heaven, this pretty
  Is sweetness itself to everybody
  Woe is me!  I cry to the world
  Listen, everyone!  I have lost my girl.

–Guillame de Machant was the principal poet and composer to use the rondeau in fourteenth-century France.  He wrote less than 30 musical rondeaux, but brought attention to the form through his innovative combinations of highly intimate, prayerful text with strict adherence to form.  "By the middle of the fifteenth century, [the rondeau] had virtually supplanted the other song forms" (www.britannica.com).  At this time, Guillame Dufay, who supervised music at the cathedral of Cambrai, further popularized the form with his numerous, upbeat, sentimental songs of love and seasons, such as his most famous--"Par le regart de vos beaux yeux," "For a Glance From Your Lovely Eyes."  Another church musician, Gilles Binchois, also advanced the rondeau with pieces such as "De Plus en Plus", "More and More."  These songs represent the peak of the rondeau's history as a musical form.

By the end of the fifteenth century, the literary rondeau had begun to clearly separate itself from song as a way of curtailing the sometimes "unwieldy" (Britannica) length of the refrains.  As text, the rondeau introduced new and exciting ways of handling refrains.  According to Helen Louise Cohen in her book, Lyric Forms from France, the refrains became shorter from the mid-fifteenth century most likely because of the scribes' practice of not writing out the full refrain of one or two lines in subsequent stanzas.   Eventually, the readers forgot the shortening of the lines was an abbreviation. 

–To hear some of Guillaume de Machaut's work, along with further discussion and illustration, visit http://www.chantboy.com/lionheart/machaut.htm

–This practice seems to be illustrated in the following segment of "The Testament" by the fifteenth century poet, François Villón (as translated by Galway Kinnell):
         
Death I appeal your harshness
Having robbed me of my mistress
You remain unsatisfied
Waiting for me to languish too
Since then I've had no strength or vigor
But in her life how did she offend you?
Death etc.

We were two, we had but one heart
Since it is dead then I must die
Yes or live without life
As images do, by heart
Death, etc.


–With only the first few words of the opening line now used as rentrement, this form allowed for new angles of meaning to be possible in the refrain, and depending on its context. The evolution of the shortened refrain has continued into modern rondeau such as Paul Laurence Dunbar's "We Wear the Mask" and Marilyn Hacker's "Rondeau After a Transatlantic Telephone Call."