I do know that a number of 11th folks were captured at Port Hudson. I have never found any hard info on why they were inside the garrison but I feel that it was most likely due to the fact they were probably sick and in garrision there and were there when the investment began. My reasons are that a number of 11th men died at PH before the investment while their regiment, the 11th and 17th were outside the garrison operating in the countryside. I am sure that the regiment came in and out of the garrison until the Union forces began their move towards the place. The men who were able then went out to scout, probe etc and the Union forces were able to put their investment into action and thus the regiments were cut off from their men still inside. Some may have been detailed for various duties inside the garrison as well. Therefore, that is the best explanation I can arrive at for their capture while the regiment was outside the works.