Explanatory Notes on the Whole Bible, by John Wesley, [1754-65], at sacred-texts.com
num 2:2His own standard - It is manifest there were four great standards or ensigns, which here follow, distinguished by their colours or figures; also there were other particular ensigns belonging to each of their fathers houses or families. Far off - Partly out of reverence to God and his worship, and the portion, allotted to it, and partly for caution, lest their vicinity to it might tempt them to make too near approaches to it. It is supposed they Were at 2000 cubits distance from it, which was the space between the people and the ark; and it is not improbable, because the Levites encamped round about it, between them and the tabernacle. It is observable, those tribes were placed together, that were nearest of kin to each other. Judah, Issachar, and Zebulun were the three youngest sons of Leah, and Issachar and Zebulun would not grudge to be under Judah, their elder brother. Reuben and Simeon would not be content with their place. Therefore Reuben, Jacob's eldest son, is chief of the next squadron. Simeon doubtless is willing to be under him. And Gad, the son of Leah's handmaid, is fitly added to him, in Levi's room. Ephraim Manasseh, and Benjamin are all the posterity of Rachel. Dan the eldest son of Bilhah leads the rest; to them are added the two younger sons of the handmaids. So much of the wisdom of God appears even in these smaller circumstances!
num 2:3Judah - This tribe was in the first post, and in their marches led the van, not only because it was the most numerous, but chiefly because Christ, the Lion of the tribe of Judah, was to descend from it: Yea, from the loins of Nahshon, who is here appointed the chief captain of it.
num 2:17In the midst - This is not to be understood strictly, but largely; for in their march they were divided, and part of that tribe marched next after Judah, Num 10:17, and the other part exactly in the midst of the camp.
num 2:18Ephraim - Who is here preferred before his brother, according to the prophecy, Gen 48:19-20.
num 2:31The Camp of Dan - The strongest camp next after Judah, and therefore he comes in the rear, as Judah marched in the front, that the tabernacle might be best guarded where there was most danger.