This publication provides fundamental principles and guidance to assist joint force commanders (JFCs), their staffs, and supporting and subordinate commanders in the planning, execution, and assessment of amphibious operations. An amphibious operation is a military operation launched from the sea by an amphibious force (AF), embarked in ships or craft with the primary purpose of introducing a landing force (LF) ashore to accomplish the assigned mission. An AF is an amphibious task force (ATF) and an LF together with other forces that are trained, organized, and equipped for amphibious operations. Amphibious operations apply maneuver principles to maritime power projection in joint and multinational operations. Amphibious operations can be designed to achieve operation or campaign objectives in one swift stroke; comprise the initial phase of a campaign or major operation to establish a military lodgment; serve as a supporting operation to deny the use of an area or facilities; to fix enemy forces and attention; to outflank an enemy; or to support military engagement, security cooperation, deterrence, humanitarian assistance, and civic assistance.