The backlash from suppression was something that Lincoln no longer had the energy to attend to. Not resorting to a massacre meant that there was still room for maneuver, the future could wait until after the Southern rebellion was suppressed; then it would be time to think of ways to ease relations.
The worst-case scenario was nothing more than losing the electoral votes of one state. If he lost this war and the United States were divided in two, no matter how well he managed the relationships, he would still be out.
Having just returned to Washington, President Lincoln received some bad news: neighboring Delaware still showed no sign of movement.
"What's going on, why hasn't Delaware been resolved yet?"
It was no wonder Lincoln was angry; Delaware was only nominally a Slave State, where slavery was effectively a thing of the past.
The entire state had just over 20,000 black people, of whom fewer than 1,800 were slaves.