Earliest conflict to employ industrial warfare = 1st modern war. Rail roads, telegraph, steamships, ironclad warship, and mass-produced weapons were employed extensively.
The war left 620,000 soldiers dead and many casualties. It was the deadliest military conflict in American history.
The mobilisation of civilian factories, mines, shipyards, banks, transportation and food supplies foreshadowed the impact of industrialisation in WW1&2 and subsequent conflicts.
More importantly, 3 constitutional Amendments (1865-1870): slavery was abolished, Afroamerican were considered citizens allowed to vote.
The south was dissatisfied, divided in 5 military districts and started a policy of segregation.