Theater (warfare)

In warfare, a theater or theatre is an area in which important military events occur or are in progress. A theater can include the entirety of the airspace, land and sea area that is or that may potentially become involved in war operations. In his book On War, Carl von Clausewitz defines the term Kriegstheater (translating the older, 17th-century Latin term theatrum belli) as one that: Denotes properly such a portion of the space over which war prevails as has its boundaries protected, and thus possesses a kind of independence. This protection may consist of fortresses, or important natural obstacles presented by the country, or even in 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; and consequently it is more or less in such a condition that changes which take place at other points in the seat of war have only an indirect and no direct influence upon it. To give an adequate idea of this, we may suppose that on this portion an advance is made, whilst in another quarter a retreat is taking place, or that upon the one an army is acting defensively, whilst 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. Theater of operations (TO) is a sub-area within a theater of war. The boundary of a TO is defined by the commander who is orchestrating or providing support for specific combat operations within the TO. Theater of operations is divided into strategic directions or military regions depending on whether it is a war or peacetime. The United States Armed Forces split into Unified Combatant Commands (regions) that are assigned to a particular theater of military operations. A strategic direction is a group of armies also known as a task (field) forces or battlegroups. A strategic command or direction in general essence would combine a number of tactical military formations or operational command.