Why are area's involved in a war called a theater. Like the pacific theater during world war II

It is a word of Greek origin that implies the geographic "boundaries" or "stage" within which a war was fought. It is a term used for brevity and common understanding.

Why are area's involved in a war called a theater. Like the pacific theater during world war II?lyric opera

The word theater has several meanings. Two of them are:

1) a building with a stage and audience seating for performances

2) a large geographic area where conflict occurs

Why are area's involved in a war called a theater. Like the pacific theater during world war II?imax theater opera theater

Battlefields only exist across the range of actual fighting. Fronts are only a short line that the soldiers of one nation havn't been able to cross yet. A theatre is a series of fronts. Similar to a theater, it has its own specific characters, objectives, and properties that would seem out of place in other theaters (why is hamlet talking with the Count of Monte Cristo?). I suppose they took the best word they could find for this relatively new scale of war; I believe that almost all wars until WWI were single theatre, multiple-front, or even singe-front.