Immanuel means “God with us,” and refers to the mortal Messiah (2 Nephi 17:14) The Lord spent most of his mortal ministry in the land of Galilea—the same area which is about to be overrun by the Assyrian armies. Therefore the term “thy land, O Immanuel” is referring to the area where the Lord will perform his work as the Messiah. The same interpretation applies to 2 Nephi 19:1-2.