25 Great Trans-Mississippi books (Part 2)

20. Battle on the Bay : The Civil War Struggle for Galveston by Ed Cotham.

19. A Severe and Bloody Fight: The Battle of Whitney's Lane and Military Occupation of White County, Arkansas, May and June 1862 by Scott Akridge and Emmett Powers.
(comment: best example of local history I've seen for the T-M region. Exceptionally well-researched and packed with maps and photos. Even has an archaeology section.)

18. Blood & Treasure: Confederate Empire in the Southwest by Donald Frazier
(comment: best single-volume overview of Sibley's New Mexico campaign)

17. Scarred By War: Civil War In Southeast Louisiana by Christopher Pena
(comment: although marred by poor editing, this is the best single source on the CW in the LaFourche district of Louisiana. This volume is a revised and expanded edition of Pena's "Touched By War", with new sections on the guerrila war in 1864-5)

16. Red River Campaign: Politics and Cotton in the Civil War by Ludwell Johnson
(comment: the oldest but still the best overall treatment of the campaign)

15. The Battle of Belmont: Grant Strikes South by Nathaniel Cheairs Hughes

14. Steele’s Retreat from Camden and the Battle of Jenkins' Ferry by Ed Bearss.
(comment: although it doesn't cover events up to Camden, this is the best history of Steele's northern wing of the combined 1864 Red River Campaign. Unfortunately, I believe the new paperback edition is out of print as well)

13. The Last Battle of the Civil War: Palmetto Ranch by Jeffrey Hunt
(comment: IMO, far superior to Tucker's work on the same subject)

12. Yankee Autumn in Acadiana by David C. Edmonds
(comment: full account of the 1863 Texas Overland Expedition)

11. Wilson's Creek : The Second Battle of the Civil War and the Men Who Fought It by William Garrett Piston and Richard Hatcher
(comment: a combined social and campaign history, and a great companion to Bearss's excellent microhistory of the battle itself)