I don't think the order of August 20 is really saying the 25th La. was captured at Vicksburg. In a rather poorly written way, it appears the order refers to soldiers who were captured/paroled at Vicksburg/Port Hudson OR are on furlough west of the Mississippi River. The latter case is what probably relates to the 25th. Any soldier who was west of the river on furlough when the two strongholds fell would have found it almost impossible to cross back over to rejoin their unit east of the river. Rather than lose them altogether, it appears this was the War Dept.'s attempt to let them continue to serve in the area they were located.