The following address is a direct link to Shaun Grenan's excellent web site devoted to Zouaves: http://www.geocities.com/zouavedatabase/indiana/12thin.html
He has some interesting photos of a recreated uniform in his collection and a little background on the 12th Indiana. I've tried to contact him via email to no avail. In the interest of a more historic impression, our reenacting organization is hoping to put this uniform together for our own use. As yet we are still using the ubiquitous sack coat for most of our living histories. This is more in an effort to homogenize with the rest of our battalion.

Some basic assumptions about the 12th Indiana can be made from what we know about when they were supplied with this uniform. Shortly after their return from the forced march to "relieve" Burnside at Knoxville (December, 1863) they were issued a new uniform. The following is an exerpt from Chaplain Gage's narrative on the 12th Indiana: "On the 20th of December, the weary and worn troops were supplied with all that the Quartermaster and Commissary Department could furnish, and the Regiment appeared on dress parade, on the evening of the 23rd, with new outfit entire, presenting a striking contrast with its previous appearance."

The Regiment was sent soon after into winter quarters in Scottsboro, Alabama. The following spring and summer campaign to take Atlanta had to have been hard on every soldier's equipment. Gage's writings don't mention a further resupply of any uniform or equipment which surely must have been necessary after such an arduous campaign, so two conclusions can be made. 1), The regiment recieved replacement Zouave uniforms from Indiana when there was need or 2), Uniform and equipment may have been facilitated through the local Quartermaster's stores. I've not found much said in the Colonel of the regiment, Reuben William's war memoirs about the resupply of his men, but I've not gone very far into detail to that end.

Take into account that the regiment was sent after Hood and then returned to Atlanta just in time for the March to the Sea and through the Carolinas, there may not have been much time for reissue of uniforms, so local stores may have been the only way to clothe the men when replacements were necessary. Following that logic, you can imagine the mixed bag appearance of the Regiment during that campaign.

You may also want to check out the following, http://www.civilwarindiana.com/soldiers/reg012.html
There are several formal photos available of 12th Indiana soldiers in this uniform, but there is no reference as to when these photos were taken. Considering the newness of the appearance of these uniforms in the photos, they may have been taken in Scottsboro or perhaps after the Grand review. All of this is only supposition, and until vetted through research is totally an educated guess.

I wish you much luck and I hope you find this information, if not longwinded, useful. Perhaps you would be willing to share any research that you uncover with us. Until we speak again, God bless, Perry