Chambersburg, Pennsylvania was the only northern town damaged by intentional torching by Confederate troops.
Atlanta is the only American city destroyed by acts of war.
The Confederate action in Chambersburg occured on July 30, 1864 on the orders of the Confederate General Early. It was in retaliation for Union Magor General Hunter's burning of Virginia Military Institute and homes of Southern activists in Lexington, Va.
Confederate General John McCausland was the commander.
The Union action in Atlanta began July 28, 1864 with the beginning artillery bombardment of the area, and continued until the city was surrendered on September 2.
Sherman's troops occupied the city until November 14, 1864 when they left the city for Savannah. It was at this time that the burning began.
The relative aspects of warfare of the two events is as follows:
........................................Chambersburg................................Atlanta.......................
Time of occupation.....................8 hours......................1728 hours (72 days)............
Length of cannon seige...............0 hours....................................31 days....................
Number of invading Soldiers........800..........................................110,000..............
Number of buildings burned..........369...........................................3600.................
Per Cent of town destroyed...........18%..........................................90%...............
Number of citizens killed................0............................................10,000...............
Atlanta & Chambersburg were almost inevitable as the war ground on into its fourth year. Both sides were increasingly desperate. That is the nature of war. As Robt. E. Lee said at Maryes Heights, "It is well that war is so terrible as we should grow too fond of it."
I'm not sure what point that you were trying to make by contrasting the time-of-occupation, etc. between Atlanta & Chambersburg. Perhaps you were trying to show that one was more deliberate than the other?
There are a lot of stories surrounding the torching of Atlanta. Where the blame gets assigned depends on which story you place the most stock in.
As for Chambersburg, the accepted story around here was that Gen. McCausland demanded a gold ransom and provisions or he would put the town to the torch. Evidently, he wasn't bluffing.