Chambersburg was burned by the Confederates. But it was in during Ewells raid in 1864 at the same time that Grant was shelling Richmond and Petersburg not just the military fortifications and the Union Navy was shelling Charleston and had shelled Vicksburg with Greek Fire. Ransom or retaliation? It was occupied twice and NOT burned before or during the Gettysburg Campaign.

How much forbearance does a people have to endure the disregard of the civilized codes of war before they react in kind?

$500,000 Ransom? What was the cost of the destruction to civilian property in the south by the Union Armies of Sherman and Sheridan?