The attack on Fort Sumter forced the Upper South to choose sides. But this choice was horrendous. They had to choose between the fight against the Lower South or to fight against the Union. There were many who now accepted the Confederacy who earlier rejected secession. Thousand of them felt betrayed over the promise mad eby Lincoln to achieve a peaceful reunion by patiently waiting for Unionists to retake the power in the seceding states. Thus. The upper south had to choose.