Army Tactics, Techniques, and Procedures (ATTP) 3-34.23 describes engineer operations at echelons above brigade (EAB) combat team level. It is the engineer doctrinal manual for engineer support to division, corps, and theater army echelons. The manual is an extension of Field Manual (FM) 3-34, and is linked to joint and Army doctrine to ensure its usefulness for operational-level commanders and staff. This manual serves as a guide for the application of engineer combat power and employment of engineer forces in support of full spectrum operations primarily at higher echelons and within a joint framework. ATTP 3-34.23 consolidates doctrine previously published in three separate manuals: FM 5-71-100, FM 5-100-15, and FM 5-116. The consolidated doctrine has been updated and revised to align with revisions to FM 3-34 and other Army and joint doctrine. The manual is organized into seven chapters plus numerous appendixes to provide additional details on selected operational topics. The first three chapters follow the flow of FM 3-34 and generally describe engineer operations at higher echelons. The next three chapters focus on operations at each of the higher echelons and operational configurations. The final chapter discusses sustainment support to the engineer forces operating at these echelons. A brief description of each of the chapters is provided below: Chapter 1 describes the engineer view of the operational environment (OE) as it pertains to operations at echelons above BCT. It discusses the challenges and opportunities that translate to requirements for engineer capabilities and combat power. It describes the forces and capabilities available including joint, interagency, and multinational forces. It concludes with a discussion of categorizing capabilities within the engineer functions and synchronizing their application through the warfighting functions. Chapter 2 discusses implications of the modular force organization for operations at higher echelons.