Abstract: We explore the question Is warfare an art or a science? Using a framework of five modes of thinking based on Jungian psychology, we answer this question by reviewing the classical writings of Sun Tzu and Clausewitz, and conclude that understanding of people and lateral thinking are the most important modes of thinking associated with C2. This leads to a number of suggestions for the design of C2 Information Systems, particularly that they should provide increased emphasis on communications, group-working and brainstorming tools, and interoperability.