SMFLS5:The Sustainment & Multifunctional Logistics SMARTbook, 5th Ed. (Guide to Operational & Tactical Level Sustainment) has been completely updated for 2021. At 368 pages, SMFLS5 topics and references include the sustainment warfighting function (ADP 4-0); sustainment operations (FM 4-0), sustainment execution (logistics, financial management, personnel services, & health services support); sustainment planning; brigade support (ATP 4-90, Brigade Support Bn); division, corps & field army sustainment (ATP 4-93, Sustainment Brigade); theater support (ATP 4-94, Theater Support Command); joint logistics (JP 4-0); deployment & redeployment (ATP/JP 3-35); and more than a dozen additional new/updated Army sustainment references. The sustainment warfighting function is the related tasks and systems that provide support and services to ensure freedom of action, extended operational reach, and prolong endurance. Sustainment determines the depth and duration of Army operations. Successful sustainment enables freedom of action by increasing the number of options available to the commander. Sustainment is essential for retaining and exploiting the initiative. The sustainment warfighting function consists of four elements: logistics, financial management, personnel services and health service support. Sustainment is essential for conducting operations and generating combat power as the Army performs its strategic roles. Sustainment provides the operational commander freedom of action, operational reach, and prolonged endurance necessary to shape operational environments, prevent conflict, prevail in large-scale ground combat operations, and consolidate gains. The effectiveness of the sustainment warfighting function is dependent upon actions of units and staffs at the operational and tactical levels.