While the war in Iraq combat casualties get a lot of attention, they are still smaller than deaths from accidents (which are currently killing about a thousand troops a year.) Of course, if you are in Iraq, your risk of death due to combat is much higher (about 400 per 100,000), because only about twelve percent of the armed forces personnel are there.
The accident rate was reduced so dramatically because of several factors. Safer equipment, better practices and better training and leadership were the main elements. These efforts resulted in military personnel having about half the death rate of civilians (of the same age and gender.)
In the last two decades, the Department of Defense has reduced deaths in the military by more than half. Thats deaths from accidents, not enemy action. For the last 35 years, accidents have been the most common cause of death for military personnel. In the early 1980s, it averaged 2,300 people killed a year (or about 70 per 100,000 personnel). For the last few years its averaged less than 30 per 100,000. Even during the last two wars in the Persian Gulf, combat deaths were far less of a problem than accidents. In 1991, combat deaths were 6.9 per 100,000 troops. This was eclipsed by deaths from illness (14.5) and suicide (12).