Abstract: The Common Router Network (CRN) concept is a key enabler for a robust, scalable, and efficient wide area network infrastructure applicable for maritime or land tactical and strategic environments. Based on the open standards of Internet Protocol (IP) it provides a secure and flexible means of exchanging a wide variety of information well beyond the capability of restrictive stovepipe data links. It is fundamentally aligned with the Protected Core Network (PCN) concept initiated from a research program undertaken by the NATO C3 Agency. It defines a flexible transport infrastructure supporting military operations based on Network Centric Warfare (NCW) principles. The CRN creates a loose coupling between the information domain and transport infrastructure, focusing on providing high service availability in high-threat environments while managing the available bandwidth. This paper discusses the fundamentals of the CRN, its application in the tactical maritime, land, and strategic environments and provides examples of its use for WAN connectivity of local area networks, maritime combat system training, and at-sea collaboration supporting anti-submarine warfare.