The Previous Rebbe related that after the Alter Rebbe was released from jail, eminent Jews asked him, “Since you could have gained your release through a miracle, why did you cause Jewish people anguish by allowing yourself to be arrested and jailed for so long?”
Similarly, our Patriarch Yaakov could have overcome his brother Esav through miraculous means but instead, he sent gifts and engaged with him.
Our Rebbe uses the story of Yaakov and Esav to explain why it was necessary to put Jewish people through that hard time. The salvation associated with Yud Tes Kislev could have occurred immediately, through a miracle.
The Torah states that Yaakov told Esav, “My gift is a sacrifice offering to you”. Yaakov was a complete Tzadik, as seen by the fact that Yacov declared, “I lived with [wicked] Lavan and kept 613 mitzvahs.” He had reached such a state of perfection that he was already prepared for the revelation of Moshiach!
Therefore, Yaacov sent his gift to Esav, to help purify the world so it, too, would be fit for redemption. As is known, the world’s purification is included generally in the purification of Esav.
Yaakov sent his brother a “sacrificial gift.” In return, Yaakov reached the level of “My soul is redeemed in peace” [Poda B’Shalom Nafshi] with the permission and agreement of Esav, who represents the “other side.”
In the same way, the Alter Rebbe could have overcome his adversaries through a miracle, but the purpose and reason for his arrest was to clear the way for Jews of all generations until the coming of Moshiach.