"Half of Sherman's Army was made up of southerners. You are just citing their behaviour. They were tough, and they were well cultured in the southern arts of handling blacks."
I believe you got your numbers wrong by a large margin. And whether a few of the Union boys came from the south or not ... they marched with the Union, they represented the Union, and they left an everlasting legacy of hatred for the North!
What Sherman's men did was nothing short of criminal conduct ... Sherman himself even admitted that! "Honest Abe" looked the other way until the reports became too numerous to count. Then even he had to say something. Here is your proof -
'On August 4 (1863) W.T. Sherman in camp on Big Black River, Mississippi, wrote to Grant at Vicksburg, "The amount of burning, stealing, and plundering done by our army makes me ashamed of it. I would quit the service if I could, because I fear that we are drifting throught the worst sort of vandalism...You and I and every commander must go through the war justly chargeable with crimes at which we blush. [italics are mine]
'President Lincoln on August 14th, 1864, telegraphed Grant at City Point, "The Secretary of War and I concur that you had better confer with General [R.E.] Lee and stipulate for a mutual discontinuance of house burning and other destruction of private property". On August 17 Grant replied to Lincoln, "The best that can be done is to publish a prohibitory order against burning private property."
As to your assertion that it was Southerners against southerners is mostly air ... 'General C.B. Fisk in Saint Joseph (Mo.) on August 3 confessed to General W.S. Rosecrans, Saint Louis, "The Colorado and Kansas troops did commit many outrages."
The list of Army Units mentioned is as follows - 18th Ohio, 18th Missouri Infantry (Union), 8th Connecticut, 8th, Illinois, 8th Ohio Cavalry, 8th Tennessee Cav (Union), 81st Ohio, 89th Indiana, 82nd Ohio, 11th Kansas Cav, 11th Indiana Regt, 11th Michigan Cav., 11th Pennsylvania Cav., 15th Illinois Cav, 15th Kansas Cav, 15th Pennsylvania Ca, 5th Kansas Cav, 5th Massachussettes Cav., 5th Mass. Colored Cav, 5th Michigan cav, 5th Rhode Island Heavy Art., 5th US Colored Troops, 50th Illinois, 58th New York, 58th PA., 55th Massachussettes (colored), 52nd Ind, 56th U.S. Colored Inf, First AL Cav (Union), 1st AR Cav. (Union), 1st Batt. NY Mounted rifles, 1 NE Cav, 1st NH Cav, 1st NM Cav and others. Perhaps the Southerners may've made up 1/8 of the invading army! You have Corps and Brigades of Union soldiers involved. 5th, 10th, 14th, 1st, 6th, 16th, 2nd, 3rd, 13th. This list is not all inclusive, but gives you a list of most who were responsible.