And it came to pass that the army of the king returned, having searched in vain for the people of the Lord.
And now behold, the forces of the king were small, having been reduced, and there began to be a division among the remainder of the people.
And the lesser part began to breathe out threatenings against the king, and there began to be a great contention among them.
How was the army “reduced”? Somehow, the army just had less people than when they left. How? The scriptures don’t tell us. The above scripture, Mosiah 19:1-3, does say that some of the people started not liking the king. Maybe some of the people in the army didn’t like the king anymore and they left or were fired from the army. We can only guess.