Considering both short-term and long-term consequences, how did the nature of warfare change as a result of the Civil War?

Following the civil war, the nature of warfare in united states changed from millitary approach into political or economic approach.

As society, most part of the world have learnt that accomplishing a certain things through killings is wrong. But it still couldn't eliminate our natural tendency to compete for limited resource, so we resorted to political and economical warfare.