When this event occurred in late 1861 it was not at all clear that the North would prevail. The South won an initial encounter with the Union army at Bull Run

When this event occurred in late 1861 it was not at all clear that the North would prevail. The South won an initial encounter with the Union army at Bull Run near Washington DC in July 1861 that illustrated the poor organization of both sides and also made it clear the war would not be won swiftly by either. It was really only after Grant's victory at Vicksburg in 1863 that it became apparent to informed observers that the Union would prevail. Even so a substantial fraction of the North was in favor of a negotiated peace. George McClellan ran against Lincoln in 1864 on a peace platform. Bloody slaughters like the Union defeat at Cold Harbor in June 1864 made his platform very strong. McClellan lost but by most accounts Lincoln's campaign was saved by late victories in Georgia.