Horav S.R. Hirsch, zl, explains the practical/symbolic meaning behind the formation of the tribes as they camped and traveled. In the front, to the east, under the degel of Yehudah, were the tribes of Yehudah, Yissachar and Zevullun. To the right, in the south, under the degel of Reuven, were Reuven, Shimon and Gad. To the left, in the north, under the degel of Dan, were the tribes of Dan, Asher and Naftali. Last, in the back, opposite Shevet Yehudah, under the degel of Efraim, were Efraim, Menashe, and Binyamin. Each of the three tribes which form the leading camp is characterized for its material and spiritual attributes, thereby maintaining a balance of sorts.
Yaakov Avinu visualized Yehudah as the most prominent tribe, symbolized by his shevet, scepter, and mechokek, leadership in Torah law. Yissachar was the tribe devoted to agriculture, who consequently had leisure time for study. Zevullun was devoted to commerce, but also seems to be a leader in cultivating literature. Hence, in the leading tribes, the areas in which the material and spiritual welfare of the nation were to depend, were united. The scepter and the law, agriculture and science, commerce and literature. These two factors, the spiritual and material, combined in the leading camp and separated right and left in the subordinate camps behind it. The camp to its right consisted of Reuven, the bechor, firstborn. He was endowed with the intelligence and sensitivity for what is right and just, yet with a softness of character which ultimately denied him the firmness necessary for leadership. In conjunction with him were Shimon, quick and impulsive, the avenger of honor, and Gad, who struck swift as an arrow to avenge any unjustified attack. In other words, on Yehudah’s right there was the courage and temperament to ward off humiliation and attack – but under the aegis of moderacy and calm.
To his left, he was flanked by Dan, the tribe of deft cleverness, the consummate politician; Asher, representing refinement of taste; and Naftali, noted for his eloquence. While on the right , Reuven represented strength and force, Dan on the left symbolized a rich development in the area of culture.
On the side opposite to the eastern camp, to the west, were the tribes of Efraim, Menashe and Benyamin. Efraim and Menashe essentially represented Shevet Yosef. Based upon Yaakov Avinu’s blessing to his sons prior to his demise, Horav Hirsch suggests that Efraim and Menashe were to develop greatness and might. Bravery would be their primary attribute, which would be a wonderful supplement to Yehudah in the east in terms of national welfare. Regrettably, history indicates that instead of complementing Yehudah, the house of Yosef opposed their leadership, catalyzing a tragic rift in Klal Yisrael. Instead of planting their degel/standard behind Yehudah, they chose to go to the forefront and claim leadership. When they broke the G-d-given formation, they brought ruin upon themselves and all the other tribes that had attached themselves to them.