Sensing an opportunity to destroy Robert E. Lee's army and take the Confederate capital in Richmond, U.S. Grant ordered the Army of the Potomac to attack well-entrenched rebels seven miles from Richmond at a place called Cold Harbor.
The battle ended up as one of the war's most lopsided victories for the South, as 13,000 U.S. soldiers were casualties. The battle stoked anti-war sentiment in the North and threatened to defeat Abraham Lincoln's reelection prospects until Atlanta fell in September.
Writing his memoirs years later, Grant would call Cold Harbor the biggest mistake he made during the war. Another soldier put it better, saying "it was not war, but murder."