On May 31, as Grant's army once again swung around the right flank of Lee's army, Union cavalry seized the crossroads of Old Cold Harbor, about 10 miles northeast of the Confederate capital of Richmond, Virginia, holding it against Confederate attacks until the Union infantry arrived. Both Grant and Lee, whose armies had suffered enormous casualties in the Overland Campaign, received reinforcements. On the evening of June 1, the Union VI Corps and XVIII Corps arrived and assaulted the Confederate works to the west of the crossroads with some success.

On June 2, the remainder of both armies arrived and the Confederates built an elaborate series of fortifications 7 miles long. At dawn on June 3, three Union corps attacked the Confederate works on the southern end of the line and were easily repulsed with heavy casualties. Attempts to assault the northern end of the line and to resume the assaults on the southern were unsuccessful.

The battle caused a rise in anti-war sentiment in the Northern states. Grant became known as the "fumbling butcher" for his poor decisions. It also lowered the morale of his remaining troops. But the campaign had served Grant's purpose—as ill-advised as his attack on Cold Harbor was, Lee had lost the initiative and was forced to devote his attention to the defense of Richmond and Petersburg.

Grant said of the battle in his Personal Memoirs, "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." The armies confronted each other on these lines until the night of June 12, when Grant again advanced by his left flank, marching to the James River. In the final stage, Lee entrenched his army within besieged Petersburg before finally retreating westward across Virginia.