The Battle of Cold Harbor was fought from May 31 to June 12, 1864, with the most significant fighting occurring on June 3. It was one of the final battles of Union Lt. Gen. Ulysses S. Grant's Overland Campaign during the American Civil War, and is remembered as one of American history's bloodiest, most lopsided battles. Thousands of Union soldiers were killed or wounded in a hopeless frontal assault against the fortified positions of Confederate Gen. Robert E.