With the Ammonites under a covenant of peace, it makes sense that Moroni would fortify a line of cities in Jershon, not just its southern border, to prevent the Lamanites from destroying the Ammonites and from gaining access to the land northward. Mormon briefly refers to the latter strategic effort in Alma 50:11.
All we have to govern placement is the sequence in which the cities are captured by the Lamanites: Manti (in the land of Manti), Zeezrom, Cumeni, and Antiparah (Alma 56:14). Helaman is with the Nephite forces in Judea, which has not yet been captured by the Lamanites. Another city, unnamed, was in the vicinity of Antiparah, by the seashore, but was not captured by the Lamanites (Alma 56:31-32). Still other cities existed “on the northward” of Judea, and it was possible for the Lamanites to pass by Judea by night or by day undetected (22). The Nephites “kept spies out round about, to watch the movements of the Lamanites,” to prevent them from attacking the cities “on the northward” (22).
Antipus developed a “stratagem” against the Lamanite army in the city Antiparah. Can the playing out of this stratagem help us identify the distance between these two cities? Unfortunately, no. Using Helaman’s narrative of this operation to determine the distance between Judea and Antiparah is futile for 4 very good reasons.
1. Helaman’s focus is on the heroic role his stripling warriors played in the operation, not providing information about specific distances between cities. Helaman is not an abridger or a military man--he is a prophet. He leads his Stripling Warriors because of their affection for him, not because of any military expertise (Alma 56:5). In fact, Helaman is uncertain how to act when the stratagem develops some difficulties, much more concerned about the welfare of his Stripling Warriors than he is about the success of the military campaign (Alma 56:42).
2. Helaman’s role is to lead the Lamanite army out of Antiparah northward into a “wilderness,” not back to the city of Judea. When Helaman flees before the Lamanite pursuit, his march is "northward" (Alma 56:35). Yet, even after going a "considerable distance," he apparently does not come near to Judea because the small army left in Judea never factors into the stratagem. After camping for the night, Helaman marched with his Stripling Warriors "into the wilderness" (Alma 56:39). After a full day in the wilderness, Helaman again camps for the night. The next morning, Helaman continues his flight into the wilderness until he realizes that the Lamanites are no longer pursuing his small army. Is this wilderness between Judea and Antiparah? or to the west or east of Judea?
3. Helaman’s information about the beginning of the operation—the positioning of his and Antipus’ armies—is just too imprecise. Verse 33 tells us that Antipus did not leave Judea with his army until Helaman’s army “came near the city Antiparah.” He does not specify whether Antipus received intelligence back from Helaman that the time was right, or that Antipus knew how long it would take Helaman to get “near” the city Antiparah and simply waited that period of time. Nor does Helaman say where Antipus marched to setup his role in the operation. Finally, Helaman doesn’t provide details about how he setup his army’s role in the operation. Did he march to a position closer to Antiparah, then camp for the night so his men would be fresh and not at risk for fatigue when they came near to Antiparah and the Lamanites began their pursuit?
4. Helaman’s conclusion of the narrative is even more imprecise. Once the great battle is over, he reverts to general information about the sending of prisoners to Zarahemla and returning to Judea. He gives no indication whatsoever of how far this battle was from Judea or how long it took for his army to return to the city. His time markers illustrate quite well how generalized his information has become. He specifically dates the great battle “the third day of the seventh month” (56:42) of the “twenty and seventh year” (56:20), but his next time marker is “thus ended the twenty and eighth year” (57:5).
Helaman’s letter narrates the retaking of Antiparah and Cumeni, but does not mention Zeezrom. This may have been included in Helaman’s narrative of the Lamanite effort to retake Cumeni, in which he says that after defeat, “they were driven back to the city of Manti” (57.22).
As stated earlier, all we have to govern placement is the sequence in which the cities were captured and then retaken. None of Helaman’s narrative is precise enough to be able to determine absolute distances between the cities.