Wikipedia says this about Tennessee in the Civil War.
To a large extent, the American Civil War was fought in cities and farms of Tennessee; only Virginia saw more battles. Tennessee was the last of the Southern states to declare secession from the Union, but saw more than its share of the devastation resulting from years of warring armies criss-crossing the state. Its rivers were key arteries to the Deep South, and, from the early days of the war, Union efforts focused on securing control of those transportation routes, as well as major roads and mountain passes such as the Cumberland Gap.
A large number of important battles occurred in Tennessee, including the vicious fighting at the Battle of Shiloh, which at the time, was the deadliest battle in American history. Other large battles in Tennessee included Stones River, Chattanooga, Nashville, and Franklin.
Although the state became a part of the Confederacy, pockets of strong pro-Union sentiments remained throughout the war, particularly in the mountains in East Tennessee.
Primary Civil War engagements in Tennessee
1862
Battle of Shiloh
Hardin County, TN
April 6-7, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Capture of Forts Henry and Donelson
Stewart and Henry Counties, TN
Mid-February 1862
Links: Park Summary | CWPT | Wiki| HMDB
Memphis (I) – Joint Operations on the Mississippi
Shelby County, TN
June 6, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Chattanooga – Confederate Heartland Offensive
Hamilton County, TN
June 7-8, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Murfreesboro – Confederate Heartland Offensive
Rutherford County, TN
July 13, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Davis (Hatchie’s) Bridge
Hardeman County, TN
October 5, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Hartsville
Trousdale County, TN
December 7, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Forrest’s Jackson Tennessee Campaign
Madison County, TN
December 19, 1862
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Parker’s Crossroads
Henderson County, TN
December 31, 1862
Links: Park Summary | CWPT | Wiki| HMDB
1863
Battle of Stone’s River (Murfreesboro)
Rutherford County, TN
December 31, 1862 – January 2, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Dover
Stewart County, TN
February 3, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Thompson’s Station
Williamson County, TN
March 4-5th, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Vaught’s Hill
Rutherford County, TN
March 20, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Brentwood
Williamson County, TN
March 25th, 1863
Links: Park Summary| CWPT | Wiki| HMDB
Battle of Franklin (I)
Williamson County, TN
April 10th, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Tullahoma Campaign
Coffee County, Bedford, and Rutherford County, TN
June-July 1863
Links: Park Summary | CWPT | Wiki| HMDB
Hoover’s (Liberty) Gap – Tullahoma Campaign
Bedford and Rutherford County, TN
June 24-26, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Blountville – East Tennessee Campaign
Sullivan County, TN
September 22, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Lookout Mountain (Chattanooga)
Hamilton County, TN
September 24, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Missionary Ridge (Chattanooga)
Hamilton County, TN
September 25, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Wauhatchie
Hamilton County, Marion County, Dade County
October 28-29, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Collierville – Operations on the Memphis and Charleston Railroad
Shelby County, TN
November 3, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Fort Sanders – Knoxville Campaign
Knox County, TN
November 16, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Campbell’s Station – Knoxville Campaign
Knox County, TN
November 29, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Bean’s Station – Knoxville Campaign
Grainger County, TN
December 14, 1863
Links: Park Summary | CWPT | Wiki| HMDB
Mossy Creek – operations around Dandridge
Jefferson County, TN
December 29, 1863
Links: Park Summary | CWPT | Wiki| HMDB
1864
Dandridge – operations around Danridge
Jefferson County, TN
January 17, 1864
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Dandridge – operations around Danridge
Jefferson County, TN
January 17, 1864
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Fair Garden
Sevier County, TN
January 27, 1864
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Memphis (II) – Forest’s Defense of Mississippi
Shelby County, TN
August 21, 1864
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Johnsonville
Benton County, TN
November 4-5, 1864
Links: Park Summary | CWPT | Wiki| HMDB
Bull’s Gap – East Tennessee Campaign
Hamblen and Greene County, TN
November 11-13, 1864
Links: Park Summary | CWPT | Wiki| HMDB
Columbia – Franklin-Nashville Campaign
Maury County, TN
November 24, 1864
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Spring Hill
Hood’s Tennessee Campaign
Maury County, TN
November 29, 1864
Links: Park Summary | CWPT | Wiki| HMDB
Battle of Franklin (II)
Hood’s Tennessee Campaign
Williamson County, TN
November 30, 1864
Links: Park Summary | CWPT | Wiki | Blog | FCWRT| HMDB
Murfreesboro – Franklin-Nashville Campaign
Rutherford County, TN
December 5-7, 1864
Links: Park Summary | CWPT | Wiki| HMDB
1865
Battle of Nashville
Hood’s Tennessee Campaign
Williamson County, TN
December 15-16, 1864
Links: Park Summary | CWPT | Wiki | BONPS| HMDB