Effective rule can be achieved through dominance and submission by using violence. If the subject cannot be subdued psychologically through fear, then injury can be inflicted. If injury is not enough, then the subject can ultimately be eliminated by murder.
How it Works
The population is desensitized to violence through the media where it is overtly displayed, and portrayed culturally as the most convenient and efficient means of solving problems. Violence is also celebrated and glorified in sporting events, mass media, and video games. This desensitization to violence eventually makes it universally accepted by the populace. It has been, for example, that heavy users of violent video games are more likely to see violence as a "solution" to social problems and are more likely to ascribe negative motives to people than the average. When violence becomes the norm, it can be used overtly by the ruling class as a means of control. The glorification of domination through violent means can also be used to gain popular support for war.
Creating a culture of violence can also be used for indirectly inflicting psychological problems on the populace. When plagued with their own mental health issues and the mental health issues of the people close to them, people are much more likely not to be concerned with what the ruling class is doing and how they are doing it. Violence and the threat of violent increases fear and thus decreases the possibility of solving problems intelligently. If one can manipulate people through fear you can lead them into thinking the way you'd like to to think.
349 soldiers committed suicide in 2012, while 301 died in active combat. This was the third time in four years that suicide surpassed combat deaths among American soldiers. It is assumed though not verified through scientific study that the reasons for suicide are linked to the psychological effects of combat service. The 90 percent increase in violent sex crimes committed by active U.S. Army soldiers between 2006 and 2011 is also attributed in part to the trauma of war. Soldiers suffering post-traumatic stress, traumatic brain injury, and depression have also been shown to have higher incidences of partner abuse.
A study conducted in Lebanon revealed that civilians exposed to (armed) conflict where six times more likely to have an anxiety disorder, three times as likely to have a mood disorder, and 13 times as likely to have an impulse-control disorder as people who had not experienced such events. Less than half of the survey respondents who reported a disorder had sought any treatment - and they took an average of six years to do so. (PLoS Medicine).
PLoS Medicine, DOI: 10.1371/journal.pmed.0050061