There was a unique power that the Jewish people possessed in order to be able to conquer the two kingdoms of Sichon and Og. Those kingdoms were extremely powerful nations. In addition, they had the power of unity.
However, the power of unity that the Jewish people displayed was far greater than the unity of the kingdoms of Sichon and Og. Those kingdoms were comprised of individuals who united only for a common cause. However, the Jewish people are essentially one; creating a much greater power and thus able to overcome the mighty kingdoms of Sichon and Og.
לקו״ש כט