The outcome was a Confederate victory. The June 3 assault failed utterly to break Lee’s line. The battle as a whole cost the Union roughly 12,000 to 13,000 casualties across the twelve days against perhaps 4,500 to 5,300 Confederate, and gained, in Grant’s own assessment, nothing. It was the most one-sided beating the Army of the Potomac had taken since Marye’s Heights at Fredericksburg a year and a half before, another notorious repulse, where wave after wave of Union infantry had been cut down charging an impregnable defensive position and gained nothing for it.

Grant knew it, and said so, in the plainest words a victorious general ever used against himself. Years later, in his memoir, he wrote:

“I have always regretted that the last assault at Cold Harbor was ever made ... No advantage whatever was gained to compensate for the heavy loss we sustained.”

That regret, and the running total behind it, is what gave Grant his nickname in the Northern press: Butcher. The Overland Campaign had cost the Union something like 50,000 to 52,000 casualties in a single month, Wilderness through Cold Harbor, capped by a slaughter that bought nothing, and the papers said as much. The strategic counter-argument was real, and quieter: those same losses were grinding Lee’s irreplaceable army down toward an end the South could not survive. On the morning of June 3, that counter-argument was no comfort to anyone.

The very failure of the assault forced Grant’s hand into the move that would actually win the war. Having proven he could not break Lee head-on, Grant broke off entirely on June 12 and pulled one of the most celebrated maneuvers of the war. He slipped his whole army southeast and across the James River, on a pontoon bridge roughly 2,200 feet long, moving over 100,000 men plus their wagons, horses, mules, and cattle across the river largely without Lee noticing in time. The target on the far side was Petersburg, the rail junction south of Richmond that fed the capital. Take Petersburg’s railroads and you strangle Richmond. The assault on Petersburg opened on June 15 and grew into the Siege of Petersburg, from June 1864 to April 1865, the long entrenched endgame that finished with Lee’s surrender at Appomattox in April 1865. Cold Harbor was the last open-field battle before that siege. The most criticized day of Grant’s career produced the maneuver that doomed the Confederacy.

The deepest meaning of that pivot is who led it, and it answers the question this story opened with: what these armies were really fighting over.

When Grant’s army struck Petersburg on June 15, the opening assault was spearheaded by a division of United States Colored Troops, Black soldiers in Union uniform, under Brigadier General Edward Hinks (North), roughly 3,500 men, many of them formerly enslaved. They were not a sideshow. They led. USCT regiments overran Confederate works that morning, crossed open ground under fire, and captured a string of artillery batteries; one of those regiments took heavy losses at Baylor’s Farm doing it. Men who had been somebody’s legal property a year or two earlier took fortified cannon from the army of the slaveholding republic that had claimed to own them.

That is the whole argument of the war, standing on two pieces of ground a few days and a few miles apart. The Confederacy fought Cold Harbor to defend slavery, and behind those very trenches enslaved laborers had been forced to dig the Confederate works while free Black men a short march away prepared to fight for their own freedom. The white Union soldiers who died charging the trench at Cold Harbor and the Black Union soldiers who stormed the works at Petersburg were not in two different wars. They were two faces of one war, by 1864 explicitly fought to break a slave society, with the Emancipation Proclamation more than a year old and Black regiments now in the front line. The slaughter at Cold Harbor bought no ground on June 3. What it bought, paid out over the next ten months, was the siege that ended the Confederacy and, with it, slavery. The men with the slips of paper pinned to their coats and the men who took the guns at Petersburg were dying and fighting for the same thing.