Total war is part of it, but militarily guerrilla warfare is mostly meaningless. Compare all US military dead from Iraq vs. one day of the battle of the bulge. These tactics generally extend the fighting, but don’t accomplish that much.
Also, a lot more people where involved than you might think. “From June 2003, through September 30, 2011, there have been 26,320-27,000+ Iraqi insurgents killed based on several estimates.” Yet, “4,424 total deaths (including both killed in action and non-hostile) and 31,952 wounded in action (WIA) as a result of the Iraq War.”
Vietnam had more US dead, 58,220 including disease and suiside. But, again individual battles in other wars killed more Americans. https://www.archives.gov/research/military/vietnam-war/casua...