We have GPS guided missiles big enough to knock out entire city blocks and can see you with infrared or night-vision cameras 30,000 feet in the air and rain down 30mm cannon rounds at 3,000 rpm or fire a volley of incendiary missiles and burn you out of the trench and then blast you to hell and back a few dozen times.
Mainly Slavery, Missouri was admitted as a slave state
Conscription forces someone to go to war; no one likes to be forced to do something against their will
People forced to go to war may be putting family and friends at risk who they were taking care of.
Less people will be working if everyone is at war