From Emmanual Goldstein's book excerpted in George Orwell's 1984:
The essential act of war is destruction, not necessarily of human lives, but of the products of human labour. War is a way of shattering to pieces, or pouring into the stratosphere, or sinking in the depths of the sea, materials which might otherwise be used to make the masses too comfortable, and hence, in the long run, too intelligent. Even when weapons of war are not actually destroyed, their manufacture is still a convenient way of expending labour power without producing anything that can be consumed.