Wretchard, over at the Belmont Club, has a good post today on social network analysis freeware. Highly useful in my mappings of political patronage to ACW military careers (currently all on index cards); you'll find it helpful also for literary detective work, such as tracking themes from Republican editorials from the 1860s as they resurface as original insights in today's prize-winning nonfiction.
You could even work it to construct orders of battle, detachings and rejoinings.
Here's one linked list of products. I'll let you know the software I select.