In studies conducted at Yale University, Dr. Stanley Milgram found that people would deliver what they thought to be lethal electric charges to victims (who were actors pretending to feel the shocks) when ordered to do so by an authority figure. Soldiers are also more likely to fire when ordered to do so.

The order to fire becomes more effective with four conditions present. The presence of the authority figure is critical. Studies from World War II showed that all soldiers fired in the presence of a commanding officer, but only 15-20% did so if the commander was absent. The soldiers are more likely to respond to the order if they are bonded with and respect the officer. The commanding officer must additionally communicate clear expectations in terms of the killing behavior desired. Finally, the more legitimate the officer’s demands are, the more likely they are to be followed. For example, if an officer orders a war crime, there is more likely to be resistance. Grossman cites the Romans’ use of centurions or obedience-demanding leaders as an example of how effective such orders can be.

In contrast, when a leader is no longer able to sacrifice troops and to order that fighting continue, defeat typically ensues.