Feb. Blog Post

A post created by Matt Bayley, Junior Associate.

Conflicts between state actors and insurgent forces arise throughout the world at any given time.  Given the tumultuous state of world affairs, the United States military is tasked with defending the people and interests of the United States, as well as its allies.  While fighting in international conflicts, the United States Army requires a set of guidelines in which commanders may refer to best comply with international law.

With this in mind, “The Law of Land Warfare” (FM 27-10) was published in 1956.[1]  FM 27-10 served as a source for the United States Army to “provide authoritative guidance to military personnel on the customary and treaty law applicable to the conduct of warfare on land and to relationships between belligerents and neutral States.”[2]

After roughly sixty-three years, the United States Army updated “The Law of Land Warfare” and adopted “The Commander’s Handbook on the Law of Land Warfare” (FM 6-27).[3]  FM 6-27 ultimately serves the same purpose as its predecessor; it contains almost the same chapters and overall components of FM 27-10.[4]  However, the newer manual goes a step further than FM 27-10.  That is, FM 6-27 provides explanations on the “Law of Armed Conflict” (LOAC) to help military personnel understand the rules of international law that apply when confronting hostile forces, insurgents, or neutral parties.[5]

FM 6-27 generally follows the same general format as its predecessor.[6]  However, while the chapters in FM 6-27 almost mirror the chapters in FM 27-10, there are slight differences in the names of the chapters.[7]  In addition, the newer field manual has eight chapters instead of nine.[8]  These chapters include (1) General Background and Basic Principles of the Law of Armed Conflict; (2) Conduct of Hostilities; (3) Prisoners of War and Other Detainees; (4) The Wounded and Sick; (5) Civilians; (6) Occupation; (7) Non-Hostile Relations Between Belligerents; and (8) War Crimes and Enforcement of the Law of Armed Conflict[9]  The ninth chapter in FM 27-10, Neutrality, is not listed in the newer FM 6-27.[10]  Just like in FM 27-10, each chapter in FM 6-27 has sections and sub-sections that more closely discuss important facts that are relevant to the chapter.[11]  The sections and sub-sections remain almost identical to FM 27-10.[12]

At the end of the manual, FM 6-27 includes a list of major Law of Armed Conflict treaties and their status.[13]  In addition, FM 6-27 has a glossary that has a section with acronyms and abbreviations of terms used within the field manual.[14]  There also is a section that provides the definitions of key terms.[15]  Just like in FM 27-10, FM 6-27 also includes a general index with page numbers for terms and phrases of interest.[16]

The main difference in the content of FM 6-27 compared to FM 27-10, however, is that FM 6-27 provides more in-depth explanations in relation to the Law of Armed Conflict.[17]  In fact, while the Law of Armed Conflict is mentioned several times throughout FM 6-27, a search through FM 27-10 reveals that the older field manual does not reference the “Law of Armed Conflict” at all.[18]  The other apparent difference in structure between the two field manuals is that FM 6-27 includes tables, images, and charts within the manual’s text to give readers a visual representation of the manual’s message.[19]


[1] Michael W. Meier, Army and Marine Corps Publish New Manual: The Commander’s Handbook on the Law of Land Warfare, Just Security (small caps) (Aug. 9, 2019), https://www.justsecurity.org/65766/army-and-marine-corps-publish-new-manual-the-commanders-handbook-on-the-law-of-land-warfare.

[2] U.S. Dep’t of Army, Field Manual 27-10, The Law of Land Warfare (18 July 1956) (hereinafter FM 27-10).

[3] Meier, supra note 1.

[4] Id.

[5] Id.

[6] Meier, supra note 1.

[7] U.S. Dep’t of Army, Field Manual 6-27, The Law of Land Warfare (07 August 2019) (hereinafter FM 6-27).

[8] Id.

[9] Id.

[10] Id.

[11] Id.

[12] Id.

[13] FM 6-27, supra note 7.

[14] Id.

[15] Id.

[16] Id.

[17] Id.

[18] See generally FM 6-27, supra note 7; see also FM 27-10, supra note 2.

[19] FM 6-27, supra note 7.

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