At Cold Harbor, the Confederate Infantry had about 24 hours to dig in and prepare for an attack from the Union army. They did not waste 1 minute of that time. It was a straight up frontal assault against well prepared defensive positions. Yankee soldiers, familiar with these types of situations wrote their names on pieces of paper and pinned them to the back of their coats, so their bodies could be identified. They knew what was coming. They attacked as ordered. About 7000 men were killed or wounded in about a half hour of fighting. The attack was called off. Grant ordered another assault, but his Corp commanders convinced him that it would end no better then the first assault. He called off any further assaults at Cold Harbor. Roughly 47%
of the attacking infantry were killed, wounded, captured, or missing. In his memoires Grant states that ordering the attack at Cold Harbor was the worst decision he ever made in his career.
I'm not saying I like the guy personally, but I thought Martin Sheen turned in a credible performance in the screen version of The Killer Angels as Lee:
(Speaking to General Longstreet, who as we all know advocated doing something sane in the situation:) "But General, the enemy is here. We must whup him here, or he will whup us."