Field Manual (FM) 3-09 is the Army's keystone doctrine for fire support. This manual is a guide to action for the employment of fire support in decisive action as a part of unified land operations. The foundation of unified land operations is built on initiative, decisive action, and mission command-linked and nested through purposeful and simultaneous execution of both combined arms maneuver and wide area security-to achieve the commander's intent and desired end state (Army Doctrine Publication (ADP) 3-0). The challenges of future armed conflict make it imperative for the Army to produce leaders and forces that exhibit a high degree of operational adaptability. Achieving the necessary level of operational adaptability requires the Army to build upon a foundation of two broad responsibilities within the framework of fullspectrum operations-Army forces conduct combined arms maneuver (CAM) to gain physical, temporal, and psychological advantages over enemy organizations. Applying an expanded understanding of combined arms, Army forces integrate the combat power resident in the Army's six warfighting functions with a wide array of related civil and military capabilities to defeat enemies and seize, retain, and exploit the initiative; and Army forces conduct wide area security (WAS) to consolidate gains, stabilize environments, and ensure freedom of movement and action. This publication identifies the principles of fire support, describes the fires warfighting function in terms of its major components, functions, and required products and describes how fire support is employed in terms of the operations process. The scope of this publication is broad in its focus in order to deal with the fire support structure as a complete entity. It gives equal treatment to the diverse assets that are designated as fire support resources. The successful employment of fire support depends on the synchronization of all forms of fire support with all warfighting functions. This fire support keystone doctrinal manual should be used by commanders and staff who must employ fire support within their operations. Fire support is provided by mortars, cann field artillery, rockets, missiles, naval surface fire support (NSFS), n-Army attack helicopters, fixed-wing aircraft, and unmanned aircraft systems. Fire support may be enhanced by those systems that enable the conduct of electronic attack. This publication describes the field artillery as the principal means of fire support available to the commander, and charges the field artillery to integrate, coordinate and synchronize all available fire support with the commander's concept of operations. This is the ultimate challenge of fire support. This FM helps commanders and their fire support staff officers and fires unit commanders meet this challenge by providing a clear and concise picture of fire support and why it must work as a unified system.