Israelite Marching Order

 Parashat Beha’alot’cha occurs just over a year after the Exodus from Egypt, with the nation of Israel still encamped around Mount Sinai.

Two weeks ago, Parashat Bamidbar cited G-d’s commanding the layout of the Camp of Israel (Numbers 2). The Mishkan (Tabernacle) was in the center of the Camp, the various Levite families in close proximity surrounding it, and the Twelve Tribes surrounding them.

The time of encamping around Mount Sinai had finished, and the Jewish nation was beginning its trek home towards the Land of Israel.

The Torah details the order of breaking camp (10:14-28):

The first to leave Mount Sinai and journey towards Israel were the three Tribes encamped east of the Mishkan, led by Judah.

Then the Mishkan was taken down, and the Gershonite and Merarite Families, who carried it, followed.

Then came the three Tribes in the south, led by Reuben.

Then came the Kohathite Families, who also carried the Mishkan, and whose responsibility it was to erect it at the next station before the rest of the camp arrived.

Following them came the three Tribes on the west, led by Ephraim.

And finally, bringing up the rear, came the three Tribes to the north. Dan was the hindmost of all the Tribes. The Torah describes the Tribe of Dan as מְאַסֵּף לְכָל הַמַּחֲנֹת (10:25), the exact meaning of which is somewhat obscure.

ArtScroll translates as “the rear guard of all the camps”. JPS and Rabbi Joseph Hertz favor the translation “the rearward of all the camps”. Rabbi Joseph Hertz explains, “the work of such a rearguard would consist in collecting stragglers, in taking charge of such as had fainted by the way, and in finding and restoring lost articles”.

210 years earlier, when the sons of Israel (literally the sons of Israel, Jacob’s sons) stood before Tzafenat Pa’aneach, the governor of Egypt, whom they did not yet recognize as their little brother Joseph when he had framed the youngest son Benjamin and threatened to hold him as a slave for the rest of his life, it was Judah who seized the initiative and stepped forth, risking his own freedom and indeed his very life to intercede on Benjamin’s behalf (Genesis 44).

That responsibility should have fallen to Reuben, the oldest of the brothers. But it was Judah who demonstrated true courage, leadership, and readiness for self-sacrifice for his brother.

And therefore it was Judah who became destined for royalty when their father Jacob/Israel blessed all his sons (Genesis 49:8-12).

And so, as befits the Tribe of Royalty, Judah led the way towards the Land of Israel.

Source.  There was no disorder, the migrating Israelites were organized like a Roman legion. I think that the meaning of the Tribe of Dan being the "measef" מאסף is clear. In the army, it means the last in marching order. It does not mean that they collect anything. They are pushing the whole column ahead. Maybe I am wrong.