Notes: from: http://www.texas-brigade.com/mule.htm
The song "Here’s Your Mule" is a comical song which was very popular with the Texas Brigade. It is about a man who come to camp to sell his wares but the foolish man lets his mule mysteriously disappear, no doubt "conscripted into service for the Confederacy". The men in the Texas Brigade would use the phrase from the song "Here’s your mule" to taunt or banter with the cavalrymen. Apparently the Texans were successful in rousing the cavalry men on an occasion or two.
At Culpeper Virgina on June 8, 1863 Jeb Stuart put on a show for the army in the form of a giant review of his cavlary. General Lee was present by invention and so was General Hood. Not only was Hood present but he brought his famous Texas Brigade with him, thereby precipitating a mild crisis. Fitzhugh Lee invited Hood. To "come and see the review, and bring any of his people." Obviously "any of his people" was meant to cover his staff, but on the second day of the review the gray masses of Hood’s men emerged with glittering bayonets from the woods in the direction of the Rapidan.
"You invited me and my people. " Hood said as he shook hands with Fitz lee, "and you see I have brought them." This was indeed a crisis. If any of the members of the Texas Brigade should holler out "Here’s your mule!" at the cavalry the grand review would certainly turn into a free for all of fisticuffs. Don’t let them yell "Here’s your mule!", Fitz Lee warned. "If they do, we’ll charge you." Wade Hampton laughed. But Hood took it more seriously and bade his men not to.
Most of the members of the Texas Brigade behaved themselves that day but one of the men could not restrain himself. Turning to a comrade he said loud enough for others to hear: "Wouldn’t we clean them out, if old Hood would only let us loose on them.
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from: http://users.erols.com/kfraser/confederate/songs/mule-exp.html
Although the moments spent in actual combat were both intense and terrifying, most of a soldier's life was tedium. He was either marching from one spot to another or waiting in camp for the next battle to be fought. To stave off boredom, he employed many methods of amusement, one of which was singing. Sentimental ballads, patriotic airs, hymns, and the 1860s equivalent of today's "Top 40" songs were all included in his repertoire, but nothing filled the bill quite like humour.
One of the best loved comic songs in the Confederate Army was "Here's Your Mule," which tells the story of a hapless farmer's efforts to keep track of the wandering mule that brings him to camp to sell his produce. It was so universally known and sung that it even rated a mention in another humorous classic, "Goober Peas."
Paul Glass, writing in Singing Soldiers, sees this song as a commentary on the problem of desertion, which plagued both armies. Irwin Silber, the editor and compiler of Songs of the Civil War, suggests that it has to do with Confederate general and well-known horse liberator John Hunt Morgan. Regardless of which interpretation you prefer, it remains one of those delightful nonsense songs that spring from the minds of men with too much free time on their hands.
As to what did happen to poor old muley, a number of possibilities exist. He may, indeed, have wandered off; he may have been "borrowed" by a soldier looking for the quickest way to put distance between himself and the army; he may have been appropriated by raiders from either army and pressed into military service; or he may have found his way into the cook's stewpot (mule steaks, roasts, and stews were not unknown entrees on Confederate mess tables).