Alma 28:1 - 28:5
Alma 28:1 And now it came to pass that after the people of Ammon were established in the land of Jershon, and a church also established in the land of Jershon, and the armies of the Nephites were set round about the land of Jershon, yea, in all the borders round about the land of Zarahemla; behold the armies of the Lamanites had followed their brethren into the wilderness.
The Ammonites were now established in the land of Jershon. The church was also established among them as well. In addition, the Nephites stationed an army in accordance with the agreement made with the Nephites between them and the Lamanites. Armies were also beefed up around the land of Zarahemla as well. It was not to soon after the Ammonites were in Jershon that the Lamanite armies came to kill them and any Nephites they could.
I guess everyone knew in time the Lamanites would come after the Ammonites had escaped from the land of Nephi.
Alma 28:2 And thus there was a tremendous battle; yea, even such an one as never had been known among all the people in the land from the time Lehi left Jerusalem; yea, and tens of thousands of the Lamanites were slain and scattered abroad.
The battle that commenced between the Nephites and the Lamanites was the bloodiest in Nephite history. The Lamanites suffered large casualites and a great loss of men.
Alma 28:3 Yea, and also there was a tremendous slaughter among the people of Nephi; nevertheless, the Lamanites were driven and scattered, and the people of Nephi returned again to their land.
The Nephites also had great loss of life but the Lamanites were scattered and driven from their lands. The Nephites were able to return to their homes in safety.
Alma 28:4 And now this was a time that there was a great mourning and lamentation heard throughout all the land, among all the people of Nephi—
There was intense morning among the Nephites over the loss of good men.
Alma 28:5 Yea, the cry of widows mourning for their husbands, and also of fathers mourning for their sons, and the daughter for the brother, yea, the brother for the father; and thus the cry of mourning was heard among all of them, mourning for their kindred who had been slain.
The wife mourned for her husband, the fathers for their sons, the sister for her brother and the sons for their fathers. There was great sorrow because so many good men were killed in this battle.