Militarism is considered to be a psychosocial disease. An aetiological agent for this disease has been identified. Acting much like a computer virus, this agent is shown to produce a radical transformation of the consciousness of parties in conflict, without their realizing what has happened. This results in a paranoid illusion in the minds of both parties, an illusion made real by the fact that both parties accept it as real. To provide immunity against militarism, a psychosocial vaccine has been developed, and is described.