Your armies, so called, not from their military force or courage, but from their numbers, and the order and manner in which they came forth. See Exodus 13:18.
Related Commentaries of Exodus 12:17
Exodus 12:17
17 And ye shall observe the feast of unleavened bread; for in this selfsame day have I brought your armies out of the land of Egypt: therefore shall ye observe this day in your generations by an ordinance for ever.