Numbers 21:33
And they turned and went up by the way of Bashan: and Og the king of Bashan went out against them, he, and all his people, to the battle at Edrei. And they turned and went up by the way of Bashan: and Og the king of Bashan went out against them, he, and all his people, to the battle at Edrei.
Israel turned and went up by the way of Bashan to Edrei, where Og the king of Bashan came out against them, he and all his people, to battle. Edrei stood on the edge of a high tableland covered with jagged volcanic rocks and approachable only by narrow, steep paths, a defensive position Og had chosen so his forces could retreat into the rocky wilderness if defeated. Bashan's fortified cities and difficult terrain, Og's great strength, and his giant hosts made the encounter appear perilous. The battle came after Israel had once refused through fear to advance into Canaan, but now Moses was with them, the divine presence led them, and the ark was among them.
God promised Moses victory, and by trusting and obeying God Israel completely defeated Og and his forces and took possession of his rich land. This was part of Israel's destruction of the Amorites and taking of their land on the way to encamping in the plains of Moab by Jericho. The victory over Og strengthened Israel's confidence that God was with them as they approached Canaan.
The victory was a recent demonstration of God's power showing that to oppose Israel was to set oneself against the infinite God, and that no hostile power can prevail against Israel while the people remain faithful to God. The victory proved Israel to be a powerful people and made Balak and all Moab exceedingly terrified. The battle was one of the slayings of two kings before crossing the Jordan, and together with the miraculous passage over the swollen and impetuous Jordan it filled the kings of the Amorites and the Canaanites with terror and melted their hearts with fear.