Casualty rates have improved over time due to advances in battlefield medicine and treatment of the wounded. In the Napoleonic era, treatment was basic with field hospitals and canned food. By World War I, 8 out of 100 wounded died compared to just 0.13 out of 100 in Iraq due to new concepts like germ theory, mobile surgical hospitals near the front lines, and treatment now similar to civilian hospitals. Infection used to be the primary cause of death for soldiers but advances in sanitation, antibiotics, and trauma care have significantly reduced casualties over the centuries.