But comically folks! (after LOL for a while) Joseph Hooker commanded the Army of the Potomac in the Civil War till after he got beat by Lee at Chancellorsville. Lincoln insulted him into resigning just before Gettysburg, which was probably a Very Good Thing. But he HAD been a good general at a lower level so in late September 1863 after the Union lost the battle of Chickamauga, they shipped about 20,000 men west from the Army of the Potomac to. . . Tennessee, and put Hooker in charge of them. Did a pretty good job too. I have also heard that verse as "to fight the rebels down in Tennessee" which makes more sense, if that is what could expect in such a song.