"Which war was that?" said Winston
"Its all wars," Said the old man vaguely. (1.8.35-37)
Warfare is so it becomes hard to recognize who they're at war with. This is the manipulation of warfare of the party.
Some pictures of Warfare
This shows what warfare is really like.
This is the one who leads the party in 1984 and he's the one who tells the citizens about all the wars.
This map shows Oceania which was "always" at war with someone, to manipulate the people.
Warfare is Manipulation
Therefore warfare is used to keep the standard of living in check (or keep it as a low standard of living). They make the people think they have less resources than they do.