Mortality from all wounds decreased dramatically across the 20th century, from 8.5% among US troops in World War I, to 3.3% in World War II, to 2.4% in Korea, and leveling at 2.6% in Vietnam.

The mortality of patients with abdominal wounds in the US army declined from 21% in World War II to 12% in Korea and 4.5% in Vietnam

Also, for most of the history of warfare, at least until World War II, disease usually killed at a higher ratio than battle wounds: nearly 8:1 in the Napoleonic Wars, 4:1 in the Crimean War, 2:1 in the Civil War, 7:1 in the Spanish-American War, and 4:1 in World War I [29, 132]. In World War II, the ratio decreased to 0.1:1; in Korea and Vietnam, to 0.2:1; and in the 1992 Gulf War, to 0.1:1.

The source of these numbers is a great overview of advances in battlefield medicine over the centuries