Deuteronomy 2:25

“ This day will I begin to put the dread of you and the fear of you on the peoples who are under the whole heaven, who will hear the report about you, and will tremble, and be in anguish because of you.”

This day is the day when they ‘passed over Ar the border of Moab'. Serious battles were now beginning. Not only would they defeat the Amorites, but that defeat would echo and re-echo throughout the vicinity, including Canaan. People would begin to fear them and their approach, and tremble. That would mean that their enemies would be defeated almost before they started. Now the new generation were to benefit by what was previously promised to the previous generation if they were faithful (Deuteronomy 11:25; Deuteronomy 28:10; Exodus 15:14; Joshua 2:9; Joshua 2:11). Yahweh was again working for them.