One striking section in Fanon's book describes violent incidents that happened to his patients during the French occupation of Algeria. For example, one man who worked for the resistance found out his wife was raped by soldiers who were looking for him. He had to deal with the aftereffects of the incident, including anger at his wife and daughter, an inability to have sex, and depressive thoughts. Other people Fanon treated had similar incidents that affected their lives and personalities.

Another mental effect of colonialism that he discusses is how people have to accept a lowered status to allow the colonizers to rule over them. He says that this state is not natural and that people fight against it—which is natural. This leads to more violence from an oppressed population.

Violence is a major theme in Fanon's work. He says that the act of colonization is a violent one. People use soldiers and weapons to take over and hold an area that was not theirs to take. The only response to such violence, he concludes, is violence. This explains why the decolonization process often takes the form of violence, with activist groups fighting against the colonizers.

Another thing Fanon focuses on is the importance of the peasant class. He says that they are often left out of discussions of decolonization but should not be. Instead, people working for decolonization should find common ground with people who might live and think differently than they do. The peasants maintain some of the national identity of the country that is colonized. Working with them and helping to build on that identity can restore some of what was lost in the act of colonization.