As lethal as modern warfare has become, it's comforting to know that today's soldiers stand a better chance than ever before of surviving combat injuries. In Afghanistan, battlefield first aid, rapid evacuations, and quickly reachable military field hospitals have saved thousands of men and women who might otherwise have died. What's remarkable about these casualty management procedures is that they haven't changed that much from the 1860s, when they were introduced in the Union Army.

Innovations in battlefield medical care came about in the early part of the Civil War in response to the horrendous conditions wounded soldiers faced. A classic example was the Battle of Second Manassas (Second Bull Run to the Confederates), a clash in late August 1862 in which Confederate troops defeated Union forces. More than 22,000 soldiers were killed or wounded in the Virginia conflict-nearly 14,000 of them Federal troops.