Moses then reminded the Jewish people how the tribes of Reuben and Gad had requested the territory that had been conquered on the east bank of the Jordan River. Moses agreed to their request on the provision that they first lead the Jewish troops in the conquest of the Land of Israel to the west of the Jordan River.
The Art of Self-Sacrifice
חֲלוּצִים תַּעַבְרוּ לִפְנֵי אֲחֵיכֶם וגו': (דברים ג:יח)
[Moses told the tribes of Reuben and Gad,] “You must cross over armed before your brothers.” Deuteronomy 3:18

The conquest of the Land of Israel corresponds to our inner conquest of the animalistic side of our personalities in order to ensure that we lead our lives in a G‑dly way. The power within us that leads us into this battle – i.e., our inner tribes of Reuben and Gad – is our ability to risk our lives for our principles.

Normally, it is enough for us to recall that we would be willing to lay down our lives for our principles, and that, in essence, any threat to our Divine mission is a direct assault on our principles. Resisting our animal drives then becomes a much simpler matter.

However, when we are confronted with a general challenge to our Jewish lifestyle, we need to summon not only the recollection of our willingness to sacrifice everything for our principles, but the willingness itself. This is our ability to assert our Jewishness no matter how strong the powers of persuasion, ridicule, or compulsion that opposing forces throw at us. Our inner tribes of Reuben and Gad need to leap forth as a separate “battalion” and wipe out the enemy’s threat in one fell swoop.

By utilizing this inner strength, we can hasten the true and final Redemption, both of the Jewish people and of all humanity.1