Why was Mordechai chosen to wage battle with Haman?
Chazal say that since Hamon was from Esav, he was to be brought down by the children of Rachel Imeinu, specifically Binyomin.
Binyomin was the only brother who didn’t bow to Esav when Yaakov met his brother (he was the only brother not yet born). Because of this, Mordechai felt that he didn’t have to bow either, just as his ancestor had refrained.
Some say that all the brothers involved in the sale of Yosefhurt their father and disrespected him; only Binyamin was not involved, while Esav was famous for his adherence to the one law of Kibbud Av Va’Eim. Even Yaakov ran away from home and lost 22 years of being able to adhere to that mitzvah. Since Binyamin was the only one to be worthy in this area, he was chosen to fight against Esav, and this included his descendants (Mordechai) as well.
So we see yet another example of the way Hashem orchestrates world events for the best and still today all though evil is going on in the world we must understand that it is all part of His masterplan and that in the end we will see the fruit of His work for the best with the coming of Moshiach to bring us out of golus once and for all Bimheira b’Yomeinu. AMEN.