Contemporary national security systems face many challenges related to the changes taking place in the security and operating environments. Cognitive warfare, listed as one of such challenges, is often described as “the struggle for hearts and minds” because in cognitive warfare it is the human mind that becomes the battlefield. The aim of the paper is to identify and explore the key assumptions of cognitive warfare. The research process is focused on the following study questions: (1) What are the characteristics of cognitive warfare? (2) How can cognitive operations build an advantage over a competitor? (3) How to build resilience to cognitive operations? The analysis is based on the data collected with the use of the method of narrative literature review. Moreover, the authors’ participatory observations and lessons from national and international military research projects contributed to understanding and discussing the gist of cognitive warfare.