The room was probably filed with fear and sadness, most of the people outside might of wondered about who shot him? or what happened? or making their own assumptions to this tragic event.
This quote means that when the oppressors are punished, it shows goodness to the people that are oppressed and the sometime it doesn’t let them get away with it. But the forgiven let them continue being oppressors and it also means that the justice is denied and it is cruel to the people that are oppressed.
It was his plan to re-admit southern states into the union.
according to the plan, southern states could be added back to the union as long as 10 % of their population was willing to swear allegiance to the union
