Alma 51:11 - 51:15
Alma 51: 11 Now his armies were not so great as they had hitherto been, because of the many thousands who had been slain by the hand of the Nephites; but notwithstanding their great loss, Amalickiah had gathered together a wonderfully great army, insomuch that he feared not to come down to the land of Zarahemla.
Amalickiah’s army was not a large as in the past because of the great numbers killed by the Nephites recent encounters. But nevertheless, his army was substantial to the point that Amalickiah did not fear once again invading Nephites territory.
Alma 51: 12 Yea, even Amalickiah did himself come down, at the head of the Lamanites. And it was in the twenty and fifth year of the reign of the judges; and it was at the same time that they had begun to settle the affairs of their contentions concerning the chief judge, Pahoran.
Instead of sending others to command his armies, Amalickiah came himself. This was in the 25th year and during the time when the issue of the continuation of the form of government with judges was getting settled.
Alma 51: 13 And it came to pass that when the men who were called king-men had heard that the Lamanites were coming down to battle against them, they were glad in their hearts; and they refused to take up arms, for they were so wroth with the chief judge, and also with the people of liberty, that they would not take up arms to defend their country.
Since this issue was not going the way the kingsmen wanted, they thought that with the Lamanites beginning to invade, that they could take advantage of the situation to get their point across and therefore refused to take up arms to defend their country.
Alma 51: 14 And it came to pass that when Moroni saw this, and also saw that the Lamanites were coming into the borders of the land, he was exceedingly wroth because of the stubbornness of those people whom he had labored with so much diligence to preserve; yea, he was exceedingly wroth; his soul was filled with anger against them.
This really infuriated Moroni especially after all the efforts he and the people had made to defended themselves against the invasion of the Lamanites they knew would soon happen.
Alma 51: 15 And it came to pass that he sent a petition, with the voice of the people, unto the governor of the land, desiring that he should read it, and give him (Moroni) power to compel those dissenters to defend their country or to put them to death.
With the consent of the people, Moroni sent a letter to the land where most of the kingsmen lived telling them that they had two choices. Either they participate in the defense with force of arms or Moroni will execute anyone who refused.