This publication, Field Manual FM 6-27 MCTP 11-10C The Commander's Handbook on the Law of Land Warfare August 2019, provides guidance to Soldiers and Marines on the doctrine and practice related to customary and treaty law applicable to the conduct of warfare on land and to relationships between opposing belligerents, in order to train and prepare for combat operations. Although some of the legal principles set forth herein also apply to warfare at sea and in the air, this publication otherwise concerns itself with the rules peculiar to naval and aerial warfare only to the extent that such rules have some direct bearing on the activities of Soldiers and Marines operating on land.Commanders, staffs, and subordinates must ensure that their decisions and actions comply with applicable U.S., international, and in some cases host-nation laws and regulations. Commanders at all levels will ensure that their Soldiers or Marines operate in accordance with the law of armed conflict (LOAC) and applicable rules of engagement. This is an official publication of the U.S. Army and a referenced publication for the U.S. Marine Corps. The principal audience for this publication is Army and Marine Corps commanders as well as Army and Marine Corps judge advocates. Commanders and staffs of Army and Marine Corps headquarters serving as joint task force or multinational headquarters should also refer to applicable joint or multinational doctrine. Trainers and educators throughout the Army and Marine Corps will also use this publication where appropriate. This publication often describes legal concepts in general terms for non-lawyers rather than exhaustively.