Biblical Commentary on the Old Testament, by Carl Friedrich Keil and Franz Delitzsh, [1857-78], at sacred-texts.com
Order of the Twelve Tribes in the Camp and on the March. - Num 2:1, Num 2:2. The twelve tribes were to encamp each one by his standard, by the signs of their fathers' houses, opposite to the tabernacle (at some distance) round about, and, according to the more precise directions given afterwards, in such order that on every side of the tabernacle three tribes were encamped side by side and united under one banner, so that the twelve tribes formed four large camps or divisions of an army. Between these camps and the court surrounding the tabernacle, the three leading mishpachoth of the Levites were to be encamped on three sides, and Moses and Aaron with the sons of Aaron (i.e., the priests) upon the fourth, i.e., the front or eastern side, before the entrance (Num 3:21-38). דּגל, a standard, banner, or flag, denotes primarily the larger field sign, possessed by every division composed of three tribes, which was also the banner of the tribe at the head of each division; and secondarily, in a derivative signification, it denotes the army united under one standard, like σημεία, or vexillum. It is used thus, for example, in Num 2:17, Num 2:31, Num 2:34, and in combination with מחנה in Num 2:3, Num 2:10, Num 2:18, and Num 2:25, where "standard of the camp of Judah, Reuben, Ephraim, and Dan" signifies the hosts of the tribes arranged under these banners. אתת, the signs (ensigns), were the smaller flags or banners which were carried at the head of the different tribes and subdivisions of the tribes (the fathers' houses). Neither the Mosaic law, nor the Old Testament generally, gives us any intimation as to the form or character of the standard (degel). According to rabbinical tradition, the standard of Judah bore the figure of a lion, that of Reuben the likeness of a man or of a man's head, that of Ephraim the figure of an ox, and that of Dan the figure of an eagle; so that the four living creatures united in the cherubic forms described by Ezekiel were represented upon these four standards.
(Note: Jerome Prado, in his commentary upon Ezekiel (ch. 1 p. 44), gives the following minute description according to rabbinical tradition: "The different leaders of the tribes had their own standards, with the crests of their ancestors depicted upon them. On the east, above the tent of Naasson the first-born of Judah, there shone a standard of a green colour, this colour having been adopted by him because it was in a green stone, viz., an emerald, that the name of his forefather Judah was engraved on the breastplate of the high priest (Exo 25:15.), and on this standard there was depicted a lion, the crest and hieroglyphic of his ancestor Judah, whom Jacob had compared to a lion, saying, 'Judah is a lion's whelp.' Towards the south, above the tent of Elisur the son of Reuben, there floated a red standard, having the colour of the sardus, on which the name of his father, viz., Reuben, was engraved upon the breastplate of the high priest. The symbol depicted upon this standard was a human head, because Reuben was the first-born, and head of the family. On the west, above the tent of Elishamah the son of Ephraim, there was a golden flag, on which the head of a calf was depicted, because it was through the vision of the calves or oxen that his ancestor Joseph had predicted and provided for the famine in Egypt (Gen 41); and hence Moses, when blessing the tribe of Joseph, i.e., Ephraim (Deu 33:17), said, 'his glory is that of the first-born of a bull.' The golden splendour of the standard of Ephraim resembled that of the chrysolite, in which the name of Ephraim was engraved upon the breastplate. Towards the north, above the tent of Ahiezer the son of Dan, there floated a motley standard of white and red, like the jaspis (or, as some say, a carbuncle), in which the name of Dan was engraved upon the breastplate. The crest upon this was an eagle, the great doe to serpents, which had been chosen by the leader in the place of a serpent, because his forefather Jacob had compared Dan to a serpent, saying, 'Dan is a serpent in the way, an adder (cerastes, a horned snake) in the path;' but Ahiezer substituted the eagle, the destroyer of serpents as he shrank from carrying an adder upon his flag.")
Order of the tribes in the camp and on the march. - Num 2:3-9. The standard of the tribe of Judah was to encamp in front, namely towards the east, according to its hosts; and by its side the tribes of Issachar and Zebulun, the descendants of Leah, under the command and banner of Judah: an army of 186,400 men, which was to march out first when the camp was broken up (Num 2:9), so that Judah led the way as the champion of his brethren (Gen 49:10).
"His host, and those that were numbered of them" (cf. Num 2:6, Num 2:8, Num 2:11, etc.), i.e., the army according to its numbered men.
On the south side was the standard of Reuben, with which Simeon and Gad, descendants of Leah and her maid Zilpah, were associated, and to which they were subordinated. In Num 2:14, Reuel is a mistake for Reuel (Num 1:14; Num 7:42; Num 10:20), which is the reading given here in 118 MSS cited by Kennicott and De Rossi, in several of the ancient editions, and in the Samaritan, Vulgate, and Jonah Saad., whereas the lxx, Onk., Syr., and Pers. read Reuel. This army of 151,450 men was to break up and march as the second division.
The tabernacle, the camp of the Levites, was to break up after this in the midst of the camps (i.e., of the other tribes). "As they encamp, so shall they break up," that is to say, with Levi in the midst of the tribes, "every man in his place, according to his banner." יד, place, as in Deu 23:13; Isa 57:8.
On the west the standard of Ephraim, with the tribes of Manasseh and Benjamin, that is to say, the whole of the descendants of Rachel, 108,100 men, as the third division of the army.
Lastly, towards the north was the standard of Gad, with Asher and Naphtali, the descendants of the maids Bilhah and Zilpah, 157,600 men, who were to be the last to break up, and formed the rear on the march.
לדגליהם (according to their standards) is equivalent to לצבאתם (according to their hosts) in Num 2:9, Num 2:16, and Num 2:24, i.e., according to the hosts of which they consisted.
In Num 2:32 we have the whole number given, 603,550 men, not including the Levites (Num 2:33, see at Num 1:49); and in Num 2:34 the concluding remark as to the subsequent execution of the divine command-an anticipatory notice, as in Exo 12:50; Exo 40:16, etc.