Dictionary.net

A contention by force; or the art of paralysing the forces of an enemy.

It is either public or private. It is not intended here to speak of the latter.

Public war is either civil or national. Civil war is that which is waged between two parties, citizens or members of the same state or nation. National war is a contest between two or more independent nations) carried on by au-thority of their respective governments.

War is not only an act, but a state or condition, for nations are said to be at war not only when their armies are engaged, so as to be in the very act of contention, but also when, they have any matter of controversy or dispute subsisting between them which they are determined to decide by the use of force, and have declared publicly, or by their acts, their determination so to decide it.

National wars are said to be offensive or defensive. War is offensive on the part of that government which commits the first act of violence; it is defensive on the part of that government which receives such act; but it is very difficult to say what is the first act of violence. If a nation sees itself menaced with an attack, its first act of violence to prevent such attack, will be considered as defensive.

To legalize a war it must be declared by that branch of the government entrusted by the constitution with this power. Bro. tit., Denizen, pl. 20. And it seems it need not be declared by both the belligerent powers. Rob. Rep. 232. By the constitution of the United States, art. 1, s. 7, congress are invested with power "to declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water; and they have also the power to raise and support armies, and to provide and maintain a navy." See 8 Cranch, R. 110, 154; 1 Mason, R. 79, 81; 4 Binn. R 487. Vide, generally, Grot. B, 1, c. 1, s. 1 Rutherf. Inst. B. 1, c. 19; Bynkershoeck, Quest. Jur. Pub. lib. 1, c. 1; Lee on Capt. c. 1; Chit. Law of Nat. 28; Marten's Law of Nat. B. 8, c. 2; Phil. Ev. Index, h., t. Dane's Ab. Index, h. i.; Com. Dig. h. t. Bac. Ab. Prerogative, D 4; Merl. Repert. mot Guerre; 1 Inst. 249; Vattel, liv. 3, c. 1, §1; Mann. Com. B. 3, c. 1.