I might suggest that the fleeing Confederate troops set fire to much of Richmond since they were not interested in turning over munitions, ammo and property to the advancing Union troops. While the Union armies were no saints, the southern armies were complicit in some of their own demise.
Southern Army complicity in its own demise started when the first shots were fired at Ft. Sumpter.
The political objective was independence. How shooting at a much better armed adversary with a much larger population forwarded the cause of southern independence is a mystery.
Yeah. Like deciding to go to war in the first place.