Greg,
For you and others, I wanted to make mention of an outstanding account of the battle of Fort Donelson in the book "The Life and Wars of Gideon J. Pillow" by Dr. Nathaniel Cheairs Hughes. I was especially interested in the section regarding the breakout attempt on the 15th as the reasons for it, its tactics and execution and its aftermath are thoroughly explained.
Dr. Hughes is a contributor to the message boards and his books are listed at the the following link:
http://history-sites.com/authors.htm#hughes
Just wanted to make a little plug for Dr. Hughes book, as it related to this thread.
Jim Martin