The Confederacy fought to preserve and extend slavery. Eleven states had broken away from the United States rather than accept any limit on the enslavement of Black people, and Lee’s Army of Northern Virginia was the military shield of that slaveholding republic, the thing standing between four million enslaved people and their freedom. Grant’s new way of war, the refusal to ever let Lee rest, was aimed at destroying that shield. He could trade about 18,000 of his men for about 10,000 of Lee’s and keep marching south because the Union was no longer fighting to win a battle and go home. It was fighting to break the slaveholders’ army for good and end the institution it protected.

The most literal proof of that was in the line of march. The army that pushed into the Wilderness contained an all-Black division of United States Colored Troops, formerly enslaved and free Black men in Union uniform, part of Burnside’s (North) IX Corps, the first Black combat division to march with the Army of the Potomac, which had paraded past President Abraham Lincoln in Washington on its way to the front. One of its regiments, the 23rd USCT, had been recruited from the free men and ex-slaves of Stafford, Spotsylvania, Orange, Culpeper, and Caroline counties and the city of Fredericksburg, which is to say, from the very ground this battle was being fought on. Men who had been somebody’s legal property in these neighborhoods, in Spotsylvania and Orange, were now carrying Union rifles back across the land of their own bondage.

During the Wilderness itself, that division was guarding the army’s wagon trains, not standing in the main battle line. But the point would land just days later, a few miles south, as the campaign moved on toward Spotsylvania: the 23rd USCT would become the first Black troops to fight Robert E. Lee’s Army of Northern Virginia in directed combat, turning their rifles, for the first time, on the army that existed to keep them enslaved. The men with the most literal stake in the outcome of the entire war were the ones marching back through the woods where they had once been owned.

On the map, the Wilderness opened the Overland Campaign, the continuous six-week grind (Wilderness, then Spotsylvania, then North Anna, then Cold Harbor, then the long siege of Petersburg) that pinned Lee’s army down and never let it recover the initiative again. It proved Grant’s strategy worked: the Confederacy could not replace the men it lost, and the Union could, so the very disproportion that looked like a Union defeat was, by Grant’s cold arithmetic, a step toward Confederate collapse. It gutted Lee’s high command, costing him Longstreet for the campaign’s critical phase in a friendly-fire wound that mirrored Jackson’s a year before. And the cheering on the night march was the moment the Union army stopped expecting to lose to Lee. Under all of it ran the fact the railroad junctions and casualty tables can hide: the thicket was the object, and slavery was the reason.