Chapter 3 draws attention to some significant looseness of language in the Manual’s discussion of the application of the rules of the law of war. Somewhat distracting repetitiveness is also noted, which calls into question whether the corresponding Chapter of the Manual was subjected to adequate review before its publication. The Manual’s treatment of the status of customary rules is not entirely satisfactory and a more legally accurate view is offered in Chapter 3 of the Book. Similar inexactitude or ambiguity features in the treatment of treaty law, and is likewise corrected in the present Chapter of the Book. The Manual’s treatment of the status of the parties to an armed conflict, the application of the jus in bello, its relationship with the jus ad bellum, reciprocity and the ending of hostilities are all then evaluated and where errors are detected suggested corrections are offered where appropriate.