States are duty-bound to disseminate and ensure respect for the law of armed conflict among their personnel. A number of national military manuals have been issued to this end. But what are they exactly? What do they do? Is such a manual really necessary for a state that does not have one yet? What are the experiences of those states which already issue manuals? What areas of law should a good manual cover? These and other questions were considered at an international expert seminar held under the auspices of the Centre for International Law Research and Policy (its department Forum for International Criminal and Humanitarian Law) in Oslo, Norway, on 10 December 2007. This book records the seminar's deliberations and findings. It also contains an introductory article and a checklist prepared by the editor for the benefit of those considering writing a new manual. The editor Nobuo Hayashi is an Associate Senior Lecturer at the Centre for International and Operational Law of the Swedish Defence University. The book offers contributions by a prominent group of experts, including Roberta Arnold, William H. Boothby, Ove Bring, Arne Willy Dahl, Louise Doswald-Beck, William J. Fenrick, Dieter Fleck, Charles Garraway, Hans-Petter Gasser, Sandra Krähenmann, Marja Lehto, Göran Melander, Trygve G. Nordby, Peter Otken, Anthony P.V. Rogers, François Sénéchaud, David Turns and Wolff Henchel von Heinegg.