Theater of War
Theater of war – geographical area in which the actions of several interdependent theaters of operations can be combined under the impulse of a single commander. By extension, corresponding command echelon in the organization of the forces.
This term properly denotes such a portion of the space over which war prevails as have its boundaries protected and thus possesses a kind of independence. This protection may consist of fortresses, critical natural obstacles presented by the country, or even its being separated by a considerable distance from the rest of the space embraced in the war.—Such a portion is not a mere piece of the whole but a small whole complete in itself. Consequently, it is more or less in such a condition that changes that take place at other points in the seat of war have only an indirect and no direct influence upon it. To give a good idea of this, we may suppose that on this portion, an advance is made, while in another quarter, a retreat is taking place, or that upon the one, an army is acting defensively while an offensive is being carried on upon the other. Such a clearly defined idea as this is not capable of universal application; it is here used merely to indicate the line of distinction [Clausewitz].
Українсько-французько-англійський міжвидовий словник з тактики та логістики. Dictionnaire interamées de termes tactiques et logistiques ukrainien-français-anglais: [в 2-х т.] / Київ. нац. ун-т ім. Тараса Шевченка, Військовий ін-т, Центр розробки Доктрини p.651
Clausewitz, C. (1997) On war. Book 5. Chapter 2. Ware: Wordsworth Editions. Retrieved from: https://www.gutenberg.org/files/1946/1946-h/1946-h.htm