DECLARATION OF WAR AND ITS EFFECTS
338. War an Abnormal Relation between States. -- "War is an abnormal relation between States, and produces abnormal conditions affecting the activities and interests of individuals as well. Consequently, its Outbreak brings into existence a new set of rules affecting individuals and governments, which largely supplant or supplement those rights and obligations already existing in times of peace. In view of this fact, it is extremely important to fix upon a definite date for the beginning of these new and abnormal relations between belligerents on the one hand and the two or more belligerents on the other."1
339. Is a Declaration of War Necessary? -- The question whether a formal notice of intention or declaration of war is necessary has been a subject of much controversy. The older as well as the more recent authorities have apparently been nearly equally divided on this subject.2 And international practice has varied greatly, though in modern times declaration prior to hostilities has been, comparatively speaking, somewhat exceptional.3____________________
"An act of hostility, unless it be done in the urgency of self-preservation or by way of reprisal, is in itself a full declaration of intention; any sort of previous declaration therefore is an empty formality, unless an enemy must be given time and opportunity to put himself in a state of defense, and it is needless to say that no one asserts such quixotism to be obligatory."
On the other hand, the majority of Continental publicists have insisted upon the utility or necessity of declaration, though they appear to be almost equally divided on this point. For more or less extensive citations of the authorities, see: 2 Fauchille, p. 34; 4 Calvo, § 1906; Hall, op. cit.,446-49 and notes on pp. 448-50; Mérignhae, La guerre sur terre,29-31 n.; 2 Oppenheim ( 3d ed., pp. 136 and 137 notes); 6 P.-Fodéré, No. 2673; and Rey∘, in 14 R. D. I. P. ( 1907), 306-07 n.