This publication, Army Doctrine Publication ADP 3-0 Operational October 2017, is one of the Army's two capstone doctrine publications. ADP 3-0 presents overarching doctrinal guidance and direction for conducting operations. It constitutes the Army's view of how it conducts prompt and sustained operations on land and sets the foundation for developing the other principles, tactics, techniques, and procedures detailed in subordinate doctrine publications. The principal audience for ADP 3-0 are all the members of the Profession of Arms. ADP 3- 0 provides operational guidance for commanders, staffs, civilian leaders of the Army, trainers and educators at all echelons and forms the basis for Army education system curricula. Commanders and staffs of Army headquarters serving as joint task force or multinational headquarters should also refer to applicable joint or multination doctrine concerning the range of military operations and joint or multinational forces. The Army's contribution to Joint Operations is Unified Land Operations executed through Decisive Action and guided by Mission Command. ADP 3-0, Operations, is the Army's capstone doctrine that captures the most critical lessons from a decade of continuous small scale land combat. In this edition, we retain lessons of the past but also look to a future where large-scale ground combat against peer threats is a distinct possibility. This publication builds on the idea that success requires fully integrating Army operations with the efforts of Unified Action partners, across all domains, to achieve enduring outcomes. ADP 3-0 provides a common operational doctrine for Army forces operating across the full range of military operations in multiple domains. Army forces comprising over 180,000 Soldiers are currently conducting operations in more than 140 countries to shape operational environments, prevent aggression, defeat enemies in combat, and consolidate battlefield gains. Army forces not engaged in ongoing operations are focused on their readiness for future operations which requires effective training and professional education built on doctrine. ADP 3-0 informs the preparation for, and execution of, operations. All leaders need to understand and be familiar with it. The central idea of Unified Land Operations is that, as part of a joint force, Army forces seize, retain, and exploit the initiative to gain a position of relative advantage in order to shape the operational environment, prevent conflict, consolidate gains, and win our Nation's wars. ADP 3-0 discusses the principles of Unified Land Operations-Mission Command, Develop the Situation Through Action, Combined Arms, Adherence to the Law of War, Establish and Maintain Security, and Create Multiple Dilemmas for the Enemy. ADP 3-0 incorporates the tenets of Unified Land Operations-Simultaneity, Depth, Synchronization, and Flexibility. It emphasizes operational art as the connection between strategic objectives and tactical actions, and it supports a common construct for organizing both Joint and Army operations. The construct consists of the Army operations process, an operational framework for visualizing and describing operations, and combat power. ADP 3-0 serves as the common operational doctrine for the Army. Its central idea, adapted to the unique conditions of each operational environment, represents the Army's unique contribution to Unified Action. It will permeate our doctrine, our training, and our leader professional development programs.