Throughout history, military theorists have pondered the existence of a set of principles to guide soldiers in the application of force. Mass is one of the most critical components and has existed as a United States Army principle of war since 1921. The United States Army military is currently undergoing vast changes based upon societal, technological, and evolving threat-based stimuli. This thesis examines if, at the tactical level, the United States Army should redefine the principle of mass in relation to those factors. The research shows that the current definition of mass is valid. However, the Army must clearly define a full-spectrum-based operational concept to define how it envisions force employment in the future. Not only will this revised operational concept help leaders understand how the Army will fight in the information age, it will foster a much-needed change in culture inherent in transformation.