As the U.S. Army’s operational environment transitions from limited contingency operations to large-scale combat operations (LSCO), the Medical Center of Excellence (MEDCoE), Directorate of Training and Doctrine (DOTD), Doctrine Literature Division (DLD) wanted FM 4-02, its Army Health System (AHS) capstone publication, to be one of the tools that assist in driving cultural changes within the Army Medicine today. This publication presents doctrine for the AHS in support of the modular force by providing timely medical support to the tactical commander. It identifies medical functions and procedures essential for operations covered in other Army Operational Medicine proponent manuals. This publication depicts AHS operations from the point of injury or wounding through successive roles of care within the area of operations and evacuation to the continental United States (U.S.)-support base. It presents a stable body of operational doctrine rooted in actual military experience and serves as a foundation for the development of the rest of the Army Medicine proponent manuals on how the AHS supports unified land operations.After almost three years of revision, FM 4-02 is now available on the Army Publishing Directorate website, effective 17 November 2020. This version rescinds the previous edition published last in August 2013. As a capstone doctrine publication, FM 4-02 provides an overview of how AHS supports the U.S. Army during LSCO, which requires discussion of the multiple elements of the AHS and how they work together. While the text details these relationships, the DLD added figures to help the reader form mental maps of how it all works together. Among changes in the publication are three new figures to help the reader conceptualize how each of the 10 medical functions within the AHS supports the warfighting functions of Protection and Sustainment.The first figure visually articulates how the 10 medical functions of AHS fall under two warfighting functions: Protection and Sustainment. According to ADP 3-37 (Protection), one of the 16 primary tasks of the Protection warfighting function is to “provide FHP,” and the AHS provides FHP through the preventive and treatment aspects of the following medical functions: veterinary services, combat and operational stress control, dental services, operational public health, and laboratory services (area medical laboratory). According to ADP 4-0 (Sustainment), one of the elements of the Sustainment warfighting function is HSS, and the AHS provides HSS through medical treatment, hospitalization, medical evacuation (including medical regulating), and medical logistics (including blood management). In addition, the figure highlights the Medical Command and Control medical function that functionally aligns with the Army’s Command and Control warfighting function, according to ADP 6-0 (Mission Command: Command and Control of Army Forces).The second figure is the AHS support to LSCO logic chart, and it aligns with other higher-level doctrine publication logic charts such as ADP 3-0 and FM 3-0; ADP 4-0 and FM 4-0; and ADP 3-37. The chart depicts the Army’s four strategic roles (shape operational environment, prevent conflict, prevail or conduct large-scale ground combat operations, and consolidate gains) in support of the joint force. It discusses the Army’s Operational Concept, Unified Land Operations (ULO), which is the Army’s contribution to joint operations and unified action that is guided by Mission Command and executed through Offense, Defense, Stability and/or DSCA. The text of FM 4-02 complements this logic chart by discussing how the AHS is able to support the Army during ULO by AHS command organization supporting Army Command and Control element organizations at echelon. As AHS command organizations support the Army during ULO, they have to understand the characteristics of support, the ULO tenets, and ULO principles. This logic chart shows the six warfighting functions and where AHS support falls under Protection and Sustainment. At the bottom of the chart is the explanation of how AHS provides support to LSCO through the application of the six fundamental AHS principles that have guided the provision of AHS support on the battlefield throughout its history. The AHS principles apply across all medical functions and guide medical planners in developing operation plans (OPLANs) to ensure that the FHP and HSS support are timely, synchronized, coordinated, integrated, effective, and most importantly executable in order to:• Maintain a resilient and healthy fit force• Clear the battlefield of casualties for freedom of movement• Return Soldier’s to duty as far forward as possible• Facilitate joint health services capability integrationThe third figure illustrates the AHS Operational Framework and highlights how complex providing medical support in LSCO can and will be. The DLD produced this figure, depicting an entire AHS, to complement and conceptualize the overview provided in FM 4-02. For illustration purposes, this figure depicts AHS support to only one brigade combat team, one division, and one corps, however, large-scale ground combat operations is a sustained combat operations involving multi-corps and multi-divisions.These figures are just examples of the information you can find in FM 4-02 today. The DLD strives for doctrine to be current, relevant, well-researched, user friendly, easy to understand, less intimidating, and most importantly EXCITING again! Doctrine is only as good as the units actually reading it and incorporating it in their leading and training responsibilities; units must apply it in the conduct of operation. So get EXCITED, and download FM 4-02 from the APD and Central Army Registry websites to start reading this Operational Medicine capstone doctrine publication!