The American Civil War: Slavery, Secession, and the Struggle for Union

Gary Gallagher, a historian who has spent five decades studying the American Civil War, opens with a crisp distinction that frames the entire conversation: "If you take slavery out of the picture, there is no civil war. Period." But he immediately adds a second point that complicates popular memory: most white Union soldiers did not put on blue uniforms to end slavery. They fought to preserve the Union, which they saw as a unique experiment in democratic self-government — "the last best hope of earth," as Lincoln put it. Understanding that gap between what caused the war and what motivated its soldiers is essential to understanding the conflict itself.

The Road to War: Slavery, Expansion, and Secession

The immediate cause of secession was not a debate about abolishing slavery where it already existed. The flashpoint was whether slavery would be allowed to expand into federal territories. By 1860, the free states had decisively won the population race, and white Southerners understood that if slavery could not expand, they would become a permanent minority in the national government — a government that might eventually tamper with the institution itself.