In 350 AD the Nephites entered into a treaty with the Lamanites and divided the land between them. The Nephites inherited the Northern part of the land and the Lamanites inherited the Southern part of the land, with a “narrow passage” between the two. Ten years later the Lamanites decided to attack again. (I've often wondered when, with all the battles Mormon led, he found time to abridge the sacred record he had obtained into what we know as the Book of Mormon. This peaceful decade would certainly have provided him ample opportunity.) The two armies spent a year preparing for battle and Mormon gathered his forces in the “narrow passage” of land which was the border between the two. This was sound military strategy, for the Lamanites couldn't penetrate the border to fight. Neither could they a year later when they tried it again.
We can follow Mormon’s strategy in our own battles against the influences of the adversary. Let’s not admit him into our hearts or entertain his temptations. Rather let’s cut him off at the pass as soon as he begins his attacks. The Lord is at the head of our army, and He will prevail. Let’s help Him to do so by following Him.