Unfortunately, I just remembered this from the DMG-
The overall behavior of the character (or creature) is delineated by alignment, or, in the case of player characters, behavior determines actual alignment. Therefore, besides defining the general tendencies of creatures, it also groups creatures into mutually acceptable or at least non-hostile divisions. This is not to say that groups of similarly aligned creatures cannot be opposed or even mortal enemies. Two nations, for example, with rulers of lawful good alignment can be at war. Bands of orcs can hate each other. But the former would possibly cease their war to oppose a massive invasion of orcs, just as the latter would make common cause against the lawful good men. Thus, alignment describes the world view of creatures and helps to define what their actions, reactions, and purposes will be.
GYGAX!!!!!!!!!!!