Now, the take-over of the Amorites required more than a trivial military skirmish. There are a couple of ways that Moses magnified the real grandeur of their accomplishments. First, he reminded them of just how big their chief enemy had been. King Og was such a huge giant that his iron bed had become an artifact for a museum (Deuteronomy 3:11). Og's bed was 13 feet long and 6 feet wide. That would imply that he was probably over 10 feet tall... before he attacked the Jews, that is. They defeated him and cut him down to size. Dead men aren't quite so tall.
Secondly, Moses reminded them of how many of Og's cities they had destroyed. In absolute victory, they had razed 60 walled cities. Additionally, they had won battles against a great many more little villages from the kingdom of Og. This was not a small accomplishment. By the standards of ancient warfare, there was a lot involved in defeating a city that had a wall of defense... and in wiping out an entire population. They hadn't just completely subjugated them; they had actually carried out a God ordained program of full-fledged genocide against them!