Helaman 1:22

And now when Coriantumr saw that he was in possession of the city of Zarahemla, and saw that the Nephites had fled before them, and were slain, and were taken, and were cast into prison, and that he had obtained the possession of the strongest hold in all the land, his heart took courage, insomuch that he was about to go forth against all the land.

When Coriantumr saw he had taken the city of Zarahemla, he saw the Nephites had run away. They had been killed, captured, and put in prison. He had taken the strongest place in all the land. His heart became brave. He was about to go against all the land.

Now that Coriantumr held Zarahemla—the strongest fortress in the whole land—and saw the Nephites fleeing, being killed, captured, and thrown in prison, his confidence soared. He decided to take the entire country.