I happened to notice your interest in the Battle of Ft. Bisland La. I have been researching the battle for a number of years and the best decription I have found is one that has already been mentioned. The Civil War Times article,of Sept. 1988, The Battle Bisland.
I had a great uncle,John Lawlor,who was wounded at the Battle of Ft. Bisland on April 13th 1863, and died a few days later at a field hospital in Brasher City. He was only 19 at the time.
John was in the 133rd N.Y. vol. inf. regiment.The 133rd was in the 3rd Div.,2nd Brigade, under Col. Paine.I noticed that your relative (in the 31st Mass.) was in the 3rd Div.3rd Brigade, on the opposite side of the Teche during the battle.
Another book that has a description of the battle is The Battle in the Bayou country by Morris Raphael. Its not as detailed as the North and South article.
If you have found anything else of interest please let me know.