During WW2 it seemed like Rommel would conquer EY c”v. In fact, the British were making plans to evacuate and the Jewish National Committee was making plans for a Massada-style last stand on Mt. Carmel. At the time Rav Herzog was in DC to ask FDR to bomb the tracks leading to the concentration camps. FDR said that he was willing to save one Jew – Rav Herzog – and offered him an iummigrant’s visa. Rav Herzog paskened that the Third Commonwealth would not be destroyed. The rest is history.
BTW, the Gemara (Yoma 10a) says that there will be a war between Rome and Persia. There is a machloket as to who will win. This could include a brief confrontation between Iran and Israel (Sanhedrin 98b) after which Mashiach will come.