Yeah I definitely agree with that analysis - it's much easier to finance a war by printing money.

I assumed (from the "about a third of us" bit) that he was referring to runaway inflation under the Weimar Republic leading to the rise of Hitler (who murdered ~1/3 of world Jewry). There are pictures from that era of Germans taking a wheelbarrow of cash to buy a loaf of bread. However, the runaway printing of currency was a symptom of the extortionate reparations the Brits and French forced the Germans to agree to, thus blaming fiat for genocide is questionable.

Now, fiat would be a good explanation for why WWI dragged on for so long, but I don't know to what extent the belligerent parties actually inflated their currencies.