When you read the Old Testament, the main event that stands out is the parting of the Red Sea. That is when all of the ancient world really heard of Israel and were amazed at what the Lord had done.
But when Sihon, king of the Amorites, and Og, king of Bashan (one of the last of the Rephaites (giants) – Jos 12:4) were defeated, it was head jerk up for all the peoples of the land west of the Jordan. Their defeat is mentioned several times:
And the Lord will do to them [the nations in Canaan] what he did to Sihon and Og, the kings of the Amorites, whom he destroyed along with their land.
[Rahab of Jericho] We have heard how the Lord dried up the water of the Red Sea for you when you came out of Egypt, and what you did to Sihon and Og, the two kings of the Amorites east of the Jordan, whom you completely destroyed.
[The Gibeonites] For we have heard of His fame, and all that He did in Egypt, and all that he did to the two kings of the Amorites east of the Jordan—Sihon king of Heshbon, and Og king of Bashan, who reigned in Ashtaroth.
The defeat of these two kingssounded the alarm for the land of the Canaanites/Amorites and other peoples. Along with the deliverance from Egypt, the God of Israel was powerful.
And they were right in being afraid. Joshua 12 is a historical record of all the kings that the Israelites defeated. There were 31 total in Joshua’s lifetime. To say that the Lord was with them was an understatement.
In fact, it was an important statement that Joshua defeated these kings. In the ancient world, a people was represented by the god they served. If they won in a battle, it meant that their god was most powerful. To lose in battle meant that their god was weak. A battle was more about whose god was bigger and more powerful than whose army was more big and powerful.
By Joshua winning these battles over and over, it was sending a clear message to the people of the land – Yahweh was the most powerful. He was the God of gods and LORD of lords.
The fear of the Lord was growing in the land.