For centuries, the United States Army has answered the nation’s call to defend America’s vital interests both at home and abroad. The Total Army— active, Guard and Reserve—and the Department of the Army (DA) civilians are one team, integrating their capabilities in support of the National Military Strategy and achieving military objectives that can be translated into enduring political outcomes. This Total Army is a global force, fully engaged worldwide in preventing conflict and shaping security environments. Currently, Soldiers serve on six continents while also maintaining defense of the U.S. homeland.Future Army forces will face a security environment that is unknown, unknowable and everchanging. This degree of uncertainty—never before envisioned—has led the senior Army leadership to develop a unique operating concept that relies on tailorable, scalable and expeditionary forces that are prepared—trained and ready—to meet these global challenges.2 Building on 14 years of combat experience as a multicomponent force of both active and reserve component units, the Army of the 21st century requires agile and flexible forces that are fully integrated in such a way as to leverage and sustain the unique capabilities of both components—active and reserve—in training and in wartime execution. The evolving operational environments, changing global commitments, ongoing funding issues and future force reductions require the Army to creatively plan and develop new paradigms to sustain high readiness levels in the Total Army.To maintain this total-force focus, the Army has retained a three-star command devoted to supporting and assisting Army National Guard and Army Reserve commanders to achieve readiness and reduce postmobilization training time. First Army is a multicomponent-sourced command with the critical mission of partnering with all conventional reserve component units throughout the continental United States, Puerto Rico and the U.S. Virgin Islands. It provides advice, assistance and training support to reserve component commanders and Soldiers to build collective readiness through multi-echelon, integrated training at home station and combat training center (CTC) venues. Operating within a legislative and legal framework established by statutory and regulatory provisions, First Army establishes partnerships with reserve component unit leadership to achieve directed readiness requirements. This enables the Army— via U.S. Army Forces Command (FORSCOM)—to provide combatant commanders with trained and ready forces in support of worldwide requirements.The U.S. Army’s statutory responsibility is to conduct both prompt and sustained combat on land.3 The new security environment has triggered a renewed emphasis on the “prompt”—an Army that is agile, quick to respond, adaptable and capable of early conflict resolution—without neglecting the “sustained.” Trained and ready forces across all components are an imperative in this volatile, unpredictable national security environment.