A good point. We should recall that WWI started because the assassin of the Archduke of Herzegovena complained about how pissed off he was when he had to change zlotys into mjergs everytime he crossed borders to go to work. To really find out about this very important but neglected explanation for the cause of WWI, I recommend the article, "Currency conflicts: a heuristic to the first Imperialst War," contained in the Autumn, 1991 Journal of Marxist Studies on Eastern European Currency. The author, Hukkalaka Meshabob, was an important leader of the Trotskyist current in Bulgaria that was loyal to Juan Posadas, the Argentinian leader who believed that UFOs were proof that communism existed on other planets.
Louis Proyect (http://www.panix.com/~lnp3/marxism.html)