ATP 1-05.03 establishes a common understanding, foundational concepts, and methods for advising the commander on the impact of religion on operations. ATP 1-05.03 highlights the external advisement capability for chaplains and chaplain assistants operating from battalion through echelons above Corps in support of Unified Land Operations. This Army techniques publication - Provides fundamental principles and doctrinal terminology for chaplains and chaplain assistants. Discusses the required capability external advisement. Defines and develops systematic approaches for producing and integrating a Religious Area Assessment (RAA), a running estimate and a Religious Impact Assessment (RIA). Develops systematic approaches to integrate external advisement into the operations process (plan, prepare, execute and assess). This manual contains four chapters. Chapter 1 links religious support mission, required capabilities with the requirement to advise the commander on religion and its impact on the unit mission. Chapter 2 defines religion and Soldier and leader engagements and its impact on unit mission. Chapter 3 defines a religious area analysis and its integration into the PMESSII-PT format. Chapter 4 links external advisement and the required inputs for the development of a running estimate. The six appendixes are tools to assist chaplains and chaplain assistants in planning, preparing, executing and assessing external advisement. ATP 1-05.03 applies to commanders, Chaplains, and Chaplain Assistants. This publication applies to the Active Army, the Army National Guard (ARNG), and the U.S. Army Reserve (USAR). The principles of Army religious support doctrine presented in this manual enable chaplains and assistants to apply creative, flexible, and innovative approaches to specific missions and operational environments. Chaplains and Chaplain Assistants serving in a joint force land component command or a joint task force should refer to JP 1-05 and other joint planning publications for further guidance. ATP 1-05.03 is nested with FM 1-05.