Gallagher argues that the war's central cause was the expansion of slavery into federal territories, not abolition. While slavery was the root cause, most Union soldiers fought to preserve the Union as a democratic experiment. The Confederacy, despite its states' rights rhetoric, implemented unprecedented central government measures. Gallagher contrasts Grant's strategic brilliance with Lee's aristocratic background and costly aggression, noting that Lee's prolongation of the war inadvertently aided emancipation. He questions Gettysburg as the war's turning point, highlighting Grant's victory at Vicksburg as more decisive. The discussion covers the Lost Cause narrative, which downplays slavery, and the fate of Confederate monuments, which Gallagher believes local communities should decide. Despite modern political divisions, Gallagher argues the US is not on the verge of another civil war, finding hope in the republic's resilience and trajectory.