World War I casualties
The total number of military and civilian casualties in World War I were about 40 million: estimates range from 15 to 19 million deaths and about 23 million wounded military personnel, ranking it among the deadliest conflicts in human history.
The March (1945)
The total number of US POWs in Germany was in the region of 93,000-94,000 and official sources claim that 1,121 died. The British Commonwealth total was close to 180,000 and while no accurate records exist, if a similar casualty rate is assumed, the number who died would be around 2,200. Therefore, according to a report by the US Department of Veterans' Affairs, almost 3,500 US and Commonwealth POWs died as a result of the marches. It is possible that some of these deaths occurred before the death marches, but the marches would have claimed the vast majority.