During World War I the British military condemned over 3,000 soldiers to death, but executed only approximately 12% of these soldiers; the others received commuted sentences. Many historians believe that the military command confirmed or commuted sentences for reasons unrelated to the circumstances of a particular case and that the application of the death penalty was essentially a random, "pitiless lottery." Using a dataset on all capital cases during WWI, I statically investigate this claim and find that the data are consistent with an essentially random process. Using this result, I exploit variation in commutations and executions within military units to identify the deterrent effect of the death penalty, with deterrence measured by the elapsed time within a unit between the resolution of a death sentence (i.e., a commutation or execution) and subsequent absences within that unit. Absences are measured via "wanted" lists prepared by British military police units searching for deserters. I find limited evidence that executing deserters deterred absences, while executing non-deserters and Irish soldiers, regardless of the crime, spurred absences. This finding is potentially explicable as an iatrogenic effect where minorities react negatively to state-imposed violence. * Duke University, dchen@law.duke.edu. I would like to thank