Alma 52:11 - 52:15
Alma 52: 11 And he also said unto him, I would come unto you, but behold, the Lamanites are upon us in the borders of the land by the west sea; and behold, I go against them, therefore I cannot come unto you.
Moroni also informs Teancum that he is trying to fend off the Lamanites on the borders near the west sea as they have invaded in that quarter of the land and cannot send him any reinforcements at this time.
Alma 52: 12 Now, the king (Ammoron) had departed out of the land of Zarahemla, and had made known unto the queen concerning the death of his brother, and had gathered together a large number of men, and had marched forth against the Nephites on the borders by the west sea.
What had happened was that Ammoron had returned to Lamanite capital to tell the queen that Amalickiah was dead and that he was now the king. in addition Ammoron had created another army and invaded Nephite territory near the west sea which Moroni was now trying to crush.
Alma 52: 13 And thus he was endeavoring to harass the Nephites, and to draw away a part of their forces to that part of the land, while he had commanded those whom he had left to possess the cities which he had taken, that they should also harass the Nephites on the borders by the east sea, and should take possession of their lands as much as it was in their power, according to the power of their armies.
The strategy was that by creating second front, Moroni would have to draw off some of his forces from the area now under Teancum’s command to help fend off Ammoron’s attack by the west sea. Then the Lamanite’s on the east sea side might then be able to continue their offensive.
Alma 52: 14 And thus were the Nephites in those dangerous circumstances in the ending of the twenty and sixth year of the reign of the judges over the people of Nephi.
The Nephites are this juncture were in a bind as the 26th year ended.
Alma 52: 15 But behold, it came to pass in the twenty and seventh year of the reign of the judges, that Teancum, by the command of Moroni—who had established armies to protect the south and the west borders of the land, and had begun his march towards the land Bountiful, that he might assist Teancum with his men in retaking the cities which they had lost—
Moroni now sets up armies to deal with the invading Lamanites in the west areas which would also protect the areas to the south. With that, Moroni takes more Nephite fighters and goes to Teancum’s aid so that both might be able to retake the cities that were lost to the Lamanites.