Why do you think after the war is over, the next era (Reconstruction) will be extremely violent and difficult?

Just. because formal battles have ended, does not mean both sides will accept the outcome. Prejudice and need for cheap labor was still deeply ingrained.

The confederate south had been devastated by the Civil War. Money and law enforcement from Union military would be required., for years! The US treasury did not make enough budgeted funds available for equitable reconstruction. Blocking pro-freedmen legislation.

Many of former confederate states would send pro-slavery/anti negro representatives to US House and Senate.

Political squabbling would continue with the compromise of 18xx would remove federal troops. Dominant white racist ideals would prevail. Banks not loaning to freed slaves, only at unreasonable high interest rates, would reduce business and land ownership.

6, 4, 5, 1 are true. the others are false.