Mormon 3:4. Battle Appointment
According to Mormon 3:4, the Lamanites gave the Nephites warning by letter that they were coming to battle against them. Several years later, Mormon sent a letter to the Lamanite king asking permission to gather all the Nephites in preparation for battle and took four years to do so (Mormon 6:2-5; for the timing, see Mormon 5:6 and 6:5). It seems unreasonable that opposing armies would give warning of an attack and allow the enemy time to assemble forces.
In our post-Pearl Harbor (and post 9-11) world, one expects surprise attacks by enemy forces, but it was not always so. Ancient armies assembled at given times for warfare. In the ancient Near East, for example, it was typical for rulers to assemble their troops at the end of the rainy season. In 2 Samuel 11:1 we read that “it came to pass, after the year was expired, at the time when kings go forth to battle, that David sent Joab, and his servants with him, and all Israel; and they destroyed the children of Ammon, and besieged Rabbah. But David tarried still at Jerusalem.” It was because he did not follow the custom of accompanying his army into battle that David was tempted to commit adultery with Bathsheba and ultimately to have her husband killed.
In the days of Esther, Haman sent letters to all the provinces of the Persian empire, sealed with the king’s seal, ordering people to assemble against the Jews on a given date (Esther 3:12-14). Because it was a royal command, the order could not be rescinded, but it could be countered. At the intervention of Queen Esther, a Jewess, the king allowed her cousin Mordechai to send letters to all the provinces allowing the Jews to arm themselves to defend themselves against attack on the designated date, which thereafter was celebrated as Purim (Esther 8:7-9:21).