From "Cannoneers in Gray: The Field Artillery of the Army of Tennessee,1861-1865", Larry J. Daniel:

Chapter 11 of this book begins with an accounting of the Army of Tennessee's recovery from the exhaustion brought on by the battles at Chickamauga, Lookout Mountain, Missionary Ridge, and Chattanooga.

There is an accounting of the regimen established within the Confederate encampments during the winter months following this long and arduous campaign..

The lot in life for the greyclads at this point was not a pleasant one. but on page 121, the author does say that there were a few bright moments. The Army of Tennessee took the time to observe Christmas Day1863, And he continues, "A late winter snow prompted several large snowball fights. 'Just after stable call Major Hoxton sent me word to bring my company out as he wanted to storm Major Palmer's Battalion,' wrote Lieutenant Neal of McCants's Battery. 'We captured their camp with a yell and whipped them off the ground. Everything was taken in good fun, but it was rough play. The ground was speckled with blood from bruised noses.'"

This passage is footnoted, as follows:

Neal to "Dear Emma", March 25, 1864, A. J. Neal Letters, Emory.

Now, I seem to recall seeing mention of these snowball battles in other places, even a drawing based on same, but I don't recall where at present.

Perhaps this will provide a starting point for you.