As nations move further up the development scale, they seem to become less aggressive, in Marx's view. In socialism, for example, class concerns have triumphed over nation concerns. The proletariat rules peacefully. Even under advanced capitalism peace seems to prevail, since war does not pay for the bourgeoisie. And since the world develops unevenly, it follows that at any given moment we may confront nations at several different levels of development.
War is thus firmly within the Marxian prospect.
This takes us back to the question with which Doyle started this discussion. The problem disappears for Marx when universal socialism is reached. But the road there is a dangerous one. Focus on pp. First, however, give some attention to these points in the Lenin chapter.