You should look for "Irish Rebels, Confederate Tigers: A History of the 6th Louisiana Volunteers, 1861-1865," by James P. Gannon (Savas Publishing Co., 1998). There is a good possibility that no image of Captain Cormier exists. Jim Gannon does not have one in his book, and he was pretty thorough in tracking down images of men in the regiment.

The image at Port Hudson is not of Louis A. Cormier.