Our research uses data from multiple archival sources to examine substitution among armored (tank-intensive), infantry (troop-intensive), and airborne (also troop-intensive) military units, as well as mid-war reorganizations of each type, to estimate the marginal cost of reducing U.S. fatalities in World War II, holding constant mission effectiveness, usage intensity, and task difficulty. If the government acted as though it equated marginal benefits and costs, the marginal cost figure measures the implicit value placed on soldiers' lives. Our preferred estimates indicate that infantrymen's lives were valued in 2009 dollars between $0 and $0.5 million and armored troops' lives were valued between $2 million and $6 million, relative to the efficient $1 million to $2 million 1940s-era private value of life. We find that the reorganizations of the armored and airborne divisions both increased efficiency, one by reducing costs with little increase in fatalities and the other by reducing fatalities with little increase in costs.