This 2010 report for the US Congress compares various American wars in terms of deaths and injuries suffered by the American military.
For example, 116,516 American soldiers died in World War I, with 204,022 wounded. This is a deaths/wounded ratio of 1:1.8. By World War II war had become more fatal to American soldiers, killing 405,399 and wounding 670,846, a ratio of 1:1.65. A few other wars by deaths/wounded ratios:
Korean War 1:2.8
Vietnam War 1:2.6
Persian Gulf War 1:1.2
Afghanistan War 1:4.4
Iraq War 1:7.3
We see a dramatic shift in the ratio of deaths to wounded, with far fewer troops dying by comparison with those injured. In World War II for every one man killed barely another was wounded. By the Iraq War for every one man killed another seven were wounded.
This makes sense if we consider that emergency medical technology has improved over the period. Injuries which would have killed soldiers in the past are today treated with high tech medicine, leaving soldiers alive.
Another implication is that modern wars may seem less serious than earlier conflicts simply because soldiers are now surviving horrible injuries. In the Iraq War 31,430 American troops were wounded, while 4,301 were killed. If this conflict had the same death/wounded ratio as World War II the US would be dealing with 19,048 deaths, making it appear a much more bloody struggle.