I was informed The Battle of Antietam is ranked as one of the most costly one day battles for the United States. The best estimates are over 22,000 casualties in just one day compared to about 4,500 for D-day. The Battle of the Bulge in World War 2 cost almost 90,000 men but that was over a 31 day stretch. Gettysburg had over 51,000 casualties in just three days. As a comparison the entire Revolutionary war cost nearly 25,000. Casualties for all the battles listed combine those killed, wounded and missing. Just a side note Afghanistan and Iraq together equal 6,000 from 2001 to 2012.