Highways made getting to suburbs a lot easier and a lot safer. Suburbs were also a lot safer in general than larger cites
I think it’s because of the tactics and general. Robert E Lee was deployed in the East since Richmond was their Capital. Lee was a tactically aggressive commander and far more competent than the mediocre Southern generals in the West. Though he took an enormous number of casualties, he turned back McClellan's forces in the Seven Days battles. but then Richmond fall
